Move the storage of MessageContentModels to the room

Move the storage of MessageContentModels to the room in the same manner as memeber objects to prevent duplication but mainly to make the system easier to maintain going forward with things like threads for example. This requires the creation of a MessageContentFilterModel as the same model may be used in multiple places, sometimes with the author showning sometimes not.

src/models/messagecontentmodel.h

@@ -25,11 +25,6 @@ class MessageContentModel : public QAbstractListModel
     QML_ELEMENT
     QML_UNCREATABLE("")
 
-    /**
-     * @brief Whether the author component is being shown.
-     */
-    Q_PROPERTY(bool showAuthor READ showAuthor WRITE setShowAuthor NOTIFY showAuthorChanged)
-
 public:
     enum MessageState {
         Unknown, /**< The message state is unknown. */
@@ -75,9 +70,6 @@ public:
                                  bool isPending = false,
                                  MessageContentModel *parent = nullptr);
 
-    bool showAuthor() const;
-    void setShowAuthor(bool showAuthor);
-
     /**
      * @brief Get the given role value at the given index.
      *
@@ -117,7 +109,6 @@ private:
     NeochatRoomMember *senderObject() const;
 
     MessageState m_currentState = Unknown;
-    bool m_showAuthor = true;
     bool m_isReply;
 
     void initializeModel();