Rework ActionsHandler

Rework ActionsHandler as static helper functions.

The functions are now invoked from ChatBarCache so there is no need to pass an actions handler object around qml simplifying the code.

src/chatbarcache.h

@@ -202,6 +202,11 @@ public:
      */
     void setSavedText(const QString &savedText);
 
+    /**
+     * @brief Post the contents of the cache as a message in the room.
+     */
+    Q_INVOKABLE void postMessage();
+
 Q_SIGNALS:
     void textChanged();
     void relationIdChanged(const QString &oldEventId, const QString &newEventId);