fix: Fixes for nested dashboards/deephaven.ui (#2648)

- Add a class name for widgets loaded from the widget-loader so we know
what kind of panel it is
- Allows specific styling to be applied for panels loaded with
widget-loader
- Add metadata to widget component props type
  - It's already gets passed through, just adding it to the type
- Tested with #2648

Author: mofojed

packages/dashboard-core-plugins/src/WidgetLoaderPlugin.tsx

@@ -37,10 +37,12 @@ export function WrapWidgetPlugin(
     };
 
     const hasRef = canHaveRef(C);
+    const className = `widget-loader-${panelDescriptor.type}`;
 
     return (
       <WidgetPanel
         descriptor={panelDescriptor}
+        className={className}
         // eslint-disable-next-line react/jsx-props-no-spreading
         {...props}
       >

packages/plugin/src/PluginTypes.ts

@@ -1,4 +1,5 @@
 import type { BaseThemeType } from '@deephaven/components';
+import type { WidgetDescriptor } from '@deephaven/dashboard';
 import {
   type EventEmitter,
   type ItemContainer,
@@ -124,6 +125,11 @@ export interface WidgetComponentProps<T = unknown> {
    * @returns A promise that resolves to the widget data.
    */
   fetch: () => Promise<T>;
+
+  /**
+   * Descriptor of the widget, which may contain information such as the type and name of the widget.
+   */
+  metadata?: WidgetDescriptor;
   /**
    * A unique identifier for the widget.
    * dh.ui uses this to identify widgets within a dashboard or panel.