Allow blocking invites from people you don't share a room with

Matrix currently has a significant moderation loophole, thanks to
invites. Right now, anyone can invite anyone to a room - and clients
like NeoChat will gladly display these rooms to them and even give you
a notification.

However, this creates a pretty easy attack since room names and avatars
are arbitrary and this is a known vector of harassment in the Matrix
community. There's currently no tools to block this server-side, so
let's try to improve the situation where we can.

This adds a new setting to the Security page, wherein it allows you to
block invites from people you don't share a room with. This prevents the
notification from appearing and NeoChat will attempt to leave the room
immediately.

Since this depends on MSC 2666 - a currently unstable feature - the
server may not support it and NeoChat will disable the setting in this
case.

src/jobs/neochatgetcommonroomsjob.cpp

@@ -0,0 +1,14 @@
+// SPDX-FileCopyrightText: 2024 Joshua Goins <josh@redstrate.com>
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include "neochatgetcommonroomsjob.h"
+
+using namespace Quotient;
+
+NeochatGetCommonRoomsJob::NeochatGetCommonRoomsJob(const QString &userId)
+    : BaseJob(HttpVerb::Get,
+              QStringLiteral("GetCommonRoomsJob"),
+              QStringLiteral("/_matrix/client/unstable/uk.half-shot.msc2666/user/mutual_rooms").toLatin1(),
+              QUrlQuery({{QStringLiteral("user_id"), userId}}))
+{
+}

src/jobs/neochatgetcommonroomsjob.h

@@ -0,0 +1,14 @@
+// SPDX-FileCopyrightText: 2024 Joshua Goins <josh@redstrate.com>
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#pragma once
+
+#include <Quotient/jobs/basejob.h>
+#include <Quotient/omittable.h>
+
+// TODO: Upstream to libQuotient
+class NeochatGetCommonRoomsJob : public Quotient::BaseJob
+{
+public:
+    explicit NeochatGetCommonRoomsJob(const QString &userId);
+};