fix: Wrap the children of ReactPanel with an ErrorBoundary (#565)

[mofojed]

• Cherry pick of #565
• Previously, if a child of the ReactPanel threw, it would cause the panel to close, which could cause the widget to close unexpectedly.
• Instead, have the ReactPanel catch the error and display an error view.
• If any of the children of ReactPanel throw, it won't cause the panel to close. It will just show the error in the panel now.
• Tested against Core with a special branch debug-kill-table
  • Run the following snippet to create a panel with a table in it:

    from deephaven import time_table, ui
    p = ui.panel(time_table("PT1s"))

• Open the browser console, and enter the command dhKillTable(). The table stops ticking as it's closed.
• Hover the mouse over the table. This will trigger a NPE and a debugger breakpoint; hit resume a couple times until things resume. An error will be shown on the panel
• To simulate "reconnecting", then disable the FetchManager and re-enable it: dhDisableFetchManager(), dhEnableFetchManager()
  • Table should be reloaded and ticking again.

[mofojed]

The cherry-pick is already in the title (in brackets, (#565)) but I added to the description as well to be more explicit.