This will make it easier to type the raw message in
process_new_message. The blueslip error is left here
as a precaution, but I'm fairly confident that if
RawMessage and LocalMessage both have reactions then
that codeblock will never be called.
This commit implements the frontend of migrating the
`allow_edit_history` setting to `message_edit_history_visibility`.
This allows organizations, to have an intermediate setting to
view only the "Moves" history of the messages.
Fixes#21398.
Co-authored-by: Shlok Patel <shlokcpatel2001@gmail.com>
Co-authored-by: Tim Abbott <tabbott@zulip.com>
