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/QuickSwitcher.qml

@@ -0,0 +1,56 @@
+// SPDX-FileCopyrightText: 2023 Tobias Fella <tobias.fella@kde.org>
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+import QtQuick
+import QtQuick.Controls as QQC2
+import QtQuick.Layouts
+
+import org.kde.kirigami as Kirigami
+import org.kde.kitemmodels
+
+import org.kde.neochat
+
+Kirigami.SearchDialog {
+    id: root
+
+    required property NeoChatConnection connection
+
+    Shortcut {
+        sequence: "Ctrl+K"
+        onActivated: root.open()
+    }
+
+    onAccepted: if (currentItem) {
+        currentItem.clicked();
+    }
+
+    onTextChanged: RoomManager.sortFilterRoomListModel.filterText = text
+    model: RoomManager.sortFilterRoomListModel
+    emptyText: i18nc("Placeholder message", "No room found")
+    Kirigami.Action {
+        id: exploreRoomAction
+        text: i18nc("@action:button", "Explore rooms")
+        icon.name: "compass"
+        onTriggered: {
+            root.close()
+            let dialog = pageStack.pushDialogLayer(Qt.createComponent('org.kde.neochat', 'ExploreRoomsPage'), {
+                connection: root.connection
+            }, {
+                title: i18nc("@title", "Explore Rooms")
+            });
+            dialog.roomSelected.connect((roomId, displayName, avatarUrl, alias, topic, memberCount, isJoined) => {
+                RoomManager.resolveResource(roomId.length > 0 ? roomId : alias, isJoined ? "" : "join");
+            });
+        }
+    }
+
+    Component.onCompleted: emptyHelpfulAction = exploreRoomAction
+
+    parent: QQC2.Overlay.overlay
+
+    delegate: RoomDelegate {
+        connection: root.connection
+        onClicked: root.close()
+        showConfigure: false
+    }
+}