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/ManualUserDialog.qml

@@ -0,0 +1,82 @@
+// SPDX-FileCopyrightText: 2024 James Graham <james.h.graham@protonmail.com>
+// SPDX-License-Identifier: GPL-2.0-only OR GPL-3.0-only OR LicenseRef-KDE-Accepted-GPL
+
+import QtQuick
+import QtQuick.Controls as QQC2
+import QtQuick.Layouts
+
+import org.kde.kirigami as Kirigami
+import org.kde.kirigamiaddons.formcard as FormCard
+
+import org.kde.neochat
+
+Kirigami.Dialog {
+    id: root
+
+    /**
+     * @brief The connection for the current user.
+     */
+    required property NeoChatConnection connection
+
+    /**
+     * @brief Thrown when a user is selected.
+     */
+    signal userSelected
+
+    title: i18nc("@title", "User ID")
+
+    width: Math.min(QQC2.ApplicationWindow.window.width, Kirigami.Units.gridUnit * 24)
+    leftPadding: 0
+    rightPadding: 0
+    topPadding: 0
+    bottomPadding: 0
+
+    standardButtons: Kirigami.Dialog.Cancel
+    customFooterActions: [
+        Kirigami.Action {
+            enabled: userIdText.isValidText
+            text: i18n("OK")
+            icon.name: "dialog-ok"
+            onTriggered: {
+                root.connection.requestDirectChat(userIdText.text);
+                root.accept();
+            }
+        }
+    ]
+
+    contentItem: ColumnLayout {
+        spacing: 0
+        FormCard.FormTextFieldDelegate {
+            id: userIdText
+            property bool isValidText: text.match(/@(.+):(.+)/g)
+            property bool correctStart: text.startsWith("@")
+
+            label: i18n("User ID:")
+            statusMessage: {
+                if (text.length > 0 && !correctStart) {
+                    return i18n("User IDs Must start with @");
+                }
+                if (timer.running) {
+                    return "";
+                }
+                if (text.length > 0 && !isValidText) {
+                    return i18n("The input is not a valid user ID");
+                }
+                return correctStart ? "" : i18n("User IDs Must start with @");
+            }
+            status: text.length > 0 ? Kirigami.MessageType.Error : Kirigami.MessageType.Information
+
+            onTextEdited: timer.restart()
+
+            Timer {
+                id: timer
+                interval: 1000
+            }
+        }
+    }
+
+    onVisibleChanged: {
+        userIdText.forceActiveFocus();
+        timer.restart();
+    }
+}