Michael Gratton authored Apr 10, 2021 and Michael Gratton committed Apr 11, 2021

Convert Components.ConversationActions to a widget that encapsulates
selectively visible conversations action groups. Use multiple instances
of that in preference to a single shared instance that gets re-parented
as the responsive UI adjusts.

Flatten the custom widget hierarchy a bit by merging the
`ConversationActionBar` and `ConversationHeaderbar` widgets into
`MainToolbar` itself.