Implement account registration

Implements #7

src/qml/Component/Login/Username.qml

@@ -0,0 +1,46 @@
+// SPDX-FileCopyrightText: 2023 Tobias Fella <tobias.fella@kde.org>
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+import QtQuick 2.15
+import QtQuick.Controls 2.12 as QQC2
+
+import org.kde.kirigami 2.12 as Kirigami
+import org.kde.kirigamiaddons.formcard 1.0 as FormCard
+
+import org.kde.neochat 1.0
+
+LoginStep {
+    id: root
+
+    onActiveFocusChanged: if (activeFocus) usernameField.forceActiveFocus()
+
+    FormCard.FormTextFieldDelegate {
+        id: usernameField
+        label: i18n("Username:")
+        placeholderText: "user"
+        onTextChanged: timer.restart()
+        statusMessage: Registration.status === Registration.UsernameTaken ? i18n("Username unavailable") : ""
+        Keys.onReturnPressed: {
+            if (root.nextAction.enabled) {
+                root.nextAction.trigger()
+            }
+        }
+    }
+
+    Timer {
+        id: timer
+        interval: 500
+        onTriggered: Registration.username = usernameField.text
+    }
+
+    nextAction: Kirigami.Action {
+        text: Registration.status === Registration.TestingUsername ? i18n("Loading") : null
+
+        onTriggered: root.processed("qrc:/RegisterPassword.qml")
+        enabled: Registration.status === Registration.Ready
+    }
+
+    previousAction: Kirigami.Action {
+        onTriggered: root.processed("qrc:/Homeserver.qml")
+    }
+}