feat: Picker - initial scroll position

[bmingles]

NOTE: This PR depends on deephaven/deephaven-plugins#424 in order for element type checks to work for Item, Text, Section, etc.

• Refactored non-jsapi Picker to support JSX children with minimal wrapping instead of having to normalize items (Picker + ListView - icon_column #1890 should do the same for ListView, and we should be able to delete some of the normalization code)
• Updated scroll position logic to be able to traverse JSX elements
• Disable initial scrolling when children contain descriptions or sections

Testing
This illustrates different configurations and shows how initial scroll behavior differs for Pickers with plain items, descriptions, or sections:

import deephaven.ui as ui
from math import floor
import datetime

# Ticking table with initial row count of 200 that adds a row every second
initial_row_count=1000
items_table = time_table("PT1S", start_time=datetime.datetime.now() - datetime.timedelta(seconds=initial_row_count)).update([
    "Id=new Integer(i)",
    "Display=new String(`Display `+i)",
])

@ui.component
def pickers():
    value, set_value = ui.use_state('2SSS')

    def handle_change(v):
        print(v)
        set_value(v)

    on_change = ui.use_callback(handle_change, [])

    # Picker with text options
    text = ui.picker(
        label="Text",
        children=[
            'Text 1',
            'Text 2',
            'Text 3'
        ]
    )

    # Picker with boolean options
    boolean = ui.picker(
        label="Boolean",
        children=[
            True,
            False
        ]
    )

    # Picker with numeric options
    numeric = ui.picker(
        label="Numeric",
        children=[
            10,
            20,
            30
        ]
    )

    ################ Icons #######################################

    # Icons
    icons = ui.picker(
        label = "Icons",
        children = [
            item_with_icon('Add', 'vsAdd'),
            item_with_icon('Remove', 'vsRemove'),
        ]
    )

    # Icons (default selection)
    icons_default_selection = ui.picker(
        label = "Icons (default selection)",
        default_selected_key="3GGG",
        children = list(map(
            lambda args : item(args[1]) if args[0] % 7 > 0 else item_with_icon(args[1], 'vsAccount'), 
            enumerate(generate_item_texts(0, 500))))
    )

     # Icons (controlled)
    icons_controlled = ui.picker(
        label = "Icons (controlled)",
        selected_key=value,
        on_change=on_change,
        children = list(map(
            lambda args : item(args[1]) if args[0] % 7 > 0 else item_with_icon(args[1], 'vsAccount'), 
            enumerate(generate_item_texts(0, 500))))
    )

    ################ Descriptions #######################################

    # Descriptions (default selection)
    descriptions = ui.picker(
        label = "Descriptions",
        children = list(map(lambda txt : item(txt, True), generate_item_texts(0, 500)))
    )

    # Descriptions (default selection)
    descriptions_default_selection = ui.picker(
        label = "Descriptions (default selection)",
        default_selected_key="3GGG",
        children = list(map(lambda txt : item(txt, True), generate_item_texts(0, 500)))
    )

    # Descriptions (controlled)
    descriptions_controlled = ui.picker(
        label = "Descriptions (controlled)",
        selected_key=value,
        on_change=on_change,
        children = list(map(lambda txt : item(txt, True), generate_item_texts(0, 500)))
    )

    ################ Sections #######################################

    # Sections
    sections = ui.picker(
        label = "Sections (default selection)",
        children = [
            section(x, i * 10, i * 10 + 9) for i, x in enumerate(generate_item_texts(0, 19))
        ]
    )

    # Sections (default selection)
    sections_default_selection = ui.picker(
        label = "Sections (default selection)",
        default_selected_key = "3GGG",
        children = [
            section(x, i * 10, i * 10 + 9) for i, x in enumerate(generate_item_texts(0, 19))
        ]
    )

    # Sections (controlled)
    sections_controlled = ui.picker(
        label = "Sections (controlled)",
        selected_key=value,
        on_change=on_change,
        children = [
            section(x, i * 10, i * 10 + 9) for i, x in enumerate(generate_item_texts(0, 19))
        ]
    )

    ################ Tables #######################################

    table_value, set_table_value = ui.use_state('Display 824')

    # Uncontrolled table with default selection
    table = ui.picker(
        items_table,
        key_column="Display",
        label_column="Display",
        label="Table",
    )

    # Uncontrolled table with default selection
    table_default_selection = ui.picker(
        items_table,
        key_column="Display",
        label_column="Display",
        label="Table (default selection)",
        default_selected_key="Display 86",
    )

    # Controlled table
    table_controlled = ui.picker(
        items_table,
        key_column="Display",
        label_column="Display",
        label="Table (controlled)",
        on_selection_change=set_table_value,
        selected_key=table_value,
    )

    return ui.flex(
        direction="column",
        UNSAFE_style={"overflow":"scroll"},
        children = [
            ui.heading("Basic", margin=0),
            ui.flex(
                direction='row',
                children=[
                    text,
                    boolean,
                    numeric,
                ]
            ),
            ui.heading("Icons", margin=0),
            ui.flex(
                direction='row',
                children=[
                    icons,
                    icons_default_selection,
                    icons_controlled,
                ]
            ),
            ui.heading("Descriptions", margin=0),
            ui.flex(
                direction='row',
                children=[
                    descriptions,
                    descriptions_default_selection,
                    descriptions_controlled,
                ]
            ),
            ui.heading("Sections", margin=0),
            ui.flex(
                direction='row',
                children=[
                    sections,
                    sections_default_selection,
                    sections_controlled,
                ]
            ),
            ui.heading("Table", margin=0),
            ui.flex(
                direction='row',
                children=[
                    table,
                    table_default_selection,
                    table_controlled,
                ]
            )
        ],
    )

pick = pickers()

################ Helpers #######################################

# Generate a list of unique item text for a start / stop range
def generate_item_texts(start, stop):
    characters = list("ABCDEFGHIJKLMNOPQRSTUVWXYZ")
    size = len(characters)
    return [str(floor((i + start) / size)) + (characters[x % size] * 3) for i, x in enumerate(range(start, stop))]

@ui.component
def item(txt, include_description=False):
    return ui.item(
        ui.text(txt, key="label"),
        ui.text("Description " + txt, key="description", slot="description"),
        # key=txt,
        text_value=txt
    ) if include_description else ui.item(txt, text_value=txt)

@ui.component
def item_with_icon(txt, icon):
    return ui.item(
        text_value=txt,
        children=[
            ui.icon(icon),
            txt,
        ]
    )

@ui.component
def section(txt, start, end):
    return ui.section(
        title = "Section " + txt,
        children = list(map(lambda txt : item(txt), generate_item_texts(start, end)))
    )

resolves #1935

[mofojed]

Some minor cleanup, otherwise looks good.