Ensure we update the avatar item when switching to Compact mode

This fixes an always-reproducible bug by switching from Bubbles (with
"move local messages to the right" enabled) to Compact, and your
avatar is missing until you switch rooms or restart NeoChat.

The various flags to inform the rest of the delegate of the avatar were
returning true, but the actual avatar item was never created when the
option was switched on.

src/timeline/messagedelegate.cpp

@@ -419,6 +419,7 @@ void MessageDelegateBase::setCompactMode(bool compactMode)
 
     updateBackground();
     updateQuickAction();
+    updateAvatar();
 }
 
 void MessageDelegateBase::updateBackground()