Save composer state as right user when using alias

If the chat was opened under e.g. "@user1:example.org", but the
composer text is "o abc" where "o" is a composer alias for
"@other_account:example.org", save the composer text to state.json as
"@user1:example.org" and not the alias user.

TODO.md

@@ -1,6 +1,6 @@
 # TODO
 
-- composer state.json writingUserId problem?
+- model not in list error in the onri test room
 - refresh server list button
 
 - global presence control

src/gui/Pages/Chat/Composer/MessageArea.qml

@@ -102,7 +102,7 @@ HTextArea {
 
 
     saveName: "composer"
-    saveId: [chat.roomId, writingUserId]
+    saveId: [chat.roomId, chat.userId]
 
     enabled: chat.roomInfo.can_send_messages
     disabledText: qsTr("You do not have permission to post in this room")