Improve room setting

* Port away from OverlaySheet
* Use Kirigami.CategorizedSettings
* Add join rules (read only for now)

src/joinrulesevent.h

@@ -0,0 +1,29 @@
+// SPDX-FileCopyrightText: 2021 Carl Schwan <carl@carlschwan.eu>
+// SPDX-License-Identifier: LGPL-2.1-or-later
+
+#pragma once
+
+#include <events/stateevent.h>
+#include <quotient_common.h>
+
+namespace Quotient
+{
+class JoinRulesEvent : public StateEventBase
+{
+public:
+    DEFINE_EVENT_TYPEID("m.room.join_rules", JoinRulesEvent)
+
+    explicit JoinRulesEvent()
+        : StateEventBase(typeId(), matrixTypeId())
+    {
+    }
+    explicit JoinRulesEvent(const QJsonObject &obj)
+        : StateEventBase(typeId(), obj)
+    {
+    }
+
+    QString joinRule() const;
+    QJsonArray allow() const;
+};
+REGISTER_EVENT_TYPE(JoinRulesEvent)
+} // namespace Quotient