ui.dashboard - make dashboards have options like locking them from being re-arranged, or not saving dashboard_override changes so that browser refreshes reset local state

[mofojed]

• make dashboards have options like locking them from being re-arranged, or not saving dashboard_override changes so that browser refreshes reset local state

ui.dashboard spec: https://github.com/deephaven/deephaven-plugins/blob/main/plugins/ui/DESIGN.md#uidashboard

• root (just displaying content and opening a dashboard)
• label
• description
• background_color
• filters
• links
• settings
• on_focus, on_blur, on_hide, on_show, on_open, on_close