If users are only allowed to view move history, the header
is 'Message move history.' If users are allowed to view edit
and move history and the message is edited and moved, the header
is 'Message edit and move history.' Otherwise, it shows 'Message
edit history.' If the message is only moved (and not edited), it
shows 'Message move history.'
Fixes#34005.
If the organization has limited message history to moves only,
we display "MESSAGE MOVE HISTORY" for the overlay header, instead
of "MESSAGE EDIT HISTORY".
Adds a loading spinner to the message history overlay,
improving the user experience by providing visual feedback while the
message edit history is loading.
We redesign the message history modal to make it look similar to the
drafts and scheduled messages, using the shared styling/rendering
logic for that those existing elements to have a less goofy widget.
Fixes#28695.
