feat: Export plotly-express as a dashboard plugin

[vbabich]

Tested with DHE V+ (1.20231218.176) Core 0.32.1
Closes #308

BREAKING CHANGE:

• widget type in the PanelEvent.OPEN event arguments has changed from VariableDefinition to VariableDescriptor

[mattrunyon]

I think this will break plotly-express in DHC w/ dh.ui. We currently check if the plugin is the legacy format first when loading, so the legacy definition (named DashboardPlugin export) will override the preferred definition (default export of the plugin object)

[vbabich]

I added a named export for the legacy DashboardPlugin next to the default WidgetPlugin.
Updated DHE to prioritize legacy plugins until we implement WidgetLoaderPlugin in Enterprise.

[mofojed]

Side note, we have a useDashboardPanel hook that should do what we're doing here, but it would require other changes as well (since it doesn't use metadata or fetch at all). No need to worry about it here.

[mattrunyon]

I think we'll actually want DHE to register both plugins. Otherwise plotly-express won't work in dh.ui in DHE

[vbabich]

Why? What plugin type is needed for dh.ui in DHE?

[mattrunyon]

dh.ui reads the plugin registry and looks for WidgetPlugins to render widgets within panels. So if you have a dh.ui panel with a table and plotly-express plot, it needs both as WidgetPlugins to render properly. Just the DashboardPlugin won't do anything since that's listening at the dashboard level for a plotly-express widget to be opened as a panel.

[vbabich]

But it should work with just the WidgetPlugin, right? The plan is to phase out DashboardPlugin once we add support for WidgetPlugin in DHE.

[mattrunyon]

Yes once we support WidgetPlugins auto opening like in DHC, we'll only need the WidgetPlugin. I think we'll need both in the interim in DHE so that outside of dh.ui the DashboardPlugin will open the panel, but in dh.ui, the WidgetPlugin is needed so dh.ui knows how to render the widget