Adds Ctrl+Enter to send and Ctrl+Up to paste the last message

Minimizing a GroupChatControl should remove the self.correcting state to
avoid being in this state when restoring. Fixes #9580

Bugs should be fixed

is_groupchat is now a property

Fixes #9742

When using one window mode, we get the allocated size of our message control
notebook and save it before closing. The allocated width of our notebook does
not include the background-size of the Paned's separator. Calculating width
by subtracting roster_hpaned_position from allocated width of our window fixes
this.

Filters events with supplied attributes

Sync threshold options in the preferences window did not translate correctly,
Add Account was not translatable in accounts window,
Context menu Delete item was not translatable in history manager

This prevents Gajim from playing the message_sent sound multiple times