plotly-express - Update chart colors when theme changes

[bmingles]

Charts rendered by Plotly express plugin should update their colors when theme selection changes. We should be able to use the useTheme hook to subscribe to theme changes.

[AkshatJawne]

@mofojed Did some digging, found a couple of things
a. In the snippet you provided in the team channel, it sets color = "species", if that is removed, then the colors are correctly switching based on switching the theme. This does make sense, given if the user sets a color, even if they change their theme, the color should be the same? At least that is what I gathered from reading deephaven/web-client-ui#1772 and #251 , maybe @bmingles could further clarify this

b. In the model, at this line

deephaven-plugins/plugins/plotly-express/src/js/src/PlotlyExpressChartModel.ts

Line 243 in 453f930

removeColorsFromData(

, we use removeColorsFromData , in the definition for that function, there is a comment that "There are multiple datatypes in plotly and some don't contain marker or marker.color", which may mean that the theme cannot adjust for certain graphs that don't have the marker or marker.color , the snippet where the colors are switching is a Bar Chart, but maybe in the snippet you had provided (which is a scatter plot), there is no marker or marker.color