Update ChatDocumentHandler so RoomManger is no longer required for saving text

Update `ChatDocumentHandler` so `RoomManger` is no longer required for saving the text in the chatbar between room switches. This is achieved by allowing `ChatDocumentHandler` to get the correct `ChatBarChache` itself rather than having to have it passed from `ChatBar.qml`. This avoids any race conditions.

src/libneochat/neochatroom.cpp

@@ -2,6 +2,7 @@
 // SPDX-License-Identifier: GPL-3.0-only
 
 #include "neochatroom.h"
+#include "chatbartype.h"
 
 #include <QFileInfo>
 #include <QMediaMetaData>
@@ -1390,6 +1391,20 @@ ChatBarCache *NeoChatRoom::threadCache() const
     return m_threadCache;
 }
 
+ChatBarCache *NeoChatRoom::cacheForType(ChatBarType::Type type) const
+{
+    switch (type) {
+    case ChatBarType::Room:
+        return m_mainCache;
+    case ChatBarType::Edit:
+        return m_editCache;
+    case ChatBarType::Thread:
+        return m_threadCache;
+    default:
+        return nullptr;
+    }
+}
+
 void NeoChatRoom::replyLastMessage()
 {
     const auto &timelineBottom = messageEvents().rbegin();