Move remaining code to app module

There's still some stuff that could potentially go elsewhere but I think it's enough for now.

src/app/qml/ChooseRoomDialog.qml

@@ -0,0 +1,33 @@
+// SPDX-FileCopyrightText: 2023 Tobias Fella <tobias.fella@kde.org>
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+pragma ComponentBehavior: Bound
+
+import QtQuick
+import QtQuick.Controls
+
+import org.kde.kirigami as Kirigami
+
+import org.kde.neochat
+
+SearchPage {
+    id: root
+
+    title: i18nc("@title", "Choose a Room")
+
+    showSearchButton: false
+
+    signal chosen(string roomId)
+
+    required property NeoChatConnection connection
+
+    model: RoomManager.sortFilterRoomListModel
+    modelDelegate: RoomDelegate {
+        onClicked: {
+            root.chosen(currentRoom.id);
+            root.closeDialog();
+        }
+        connection: root.connection
+        openOnClick: false
+    }
+}