Uses Matrix's preview API to generate embedded link previews.
Only title and description for now.

This commit adds the ability to set the master push rule and set push rules for individual rooms as per the matrix spec. See https://spec.matrix.org/v1.3/client-server-api/#push-rules.
The master push rule is just on/off and uses the existing notification setting in general setting to enable/disable the server default master push rule .m.rule.master.
For each room there is now a page in the room setting that allows the following to be set:
- Default
- All messages
- @mentions and keywords
- off
New room or override rules are added/removed to achieve this.
There is also functionality to check the master/room notification state whenever the setting menu is entered. This allows the status to be updated if changed in another client or get the initial state for a room as it isn't stored.
Note - There is currently no menu items in the room list for setting the room push rule settings. This will be added in a later commit, the aim is to focus on making sure the technical implementation is good for now.
Currently when we want to show/raise the window in reaction to the tray icon/notification being clicked etc we do this by emitting a signal on the controller.
This is connected to in main.qml, which does some things, then calls back to controller to do more things.
This is quite convoluted. Instead introduce a new class WindowController that is responsible for all things window, in particular showing/raising and config saving
In the AndroidManifest we specify 'neochat' as the executable
That causes the lib to be used instead of the executable, which breaks things
Shuffle around the names so that the executable is picked
### Summary
This merge request adds a horizontal bar at top of room list, which shows spaces. By clicking on a space, user can filter out rooms belonging only to that specific space.
### Pending/ Help needed
#### Segfault when loading active connection on startup
Refer `void SortFilterRoomListModel::cacheSpaceHierarchy()` ([link](8c372800d7 (b969e462c30df43ef3714ea441948d8d8027f6a0_117_126))) in `src/sortfilterroomlistmodel.cpp`.
On [line 129](8c372800d7 (b969e462c30df43ef3714ea441948d8d8027f6a0_117_129)), I have called `connection->allRooms()`, which segfaults if the active connection hasn't been loaded yet. Is there a way to ensure that `Controller::instance().activeConnection()` on line 128 waits till connection is loaded?
#### Avatars
Avatars on space horizontal bar aren't aligned to vertical middle. I'll need help with that.
Using the code below doesn't help with padding
```qml
delegate: QQC2.Control {
topPadding: 10
contentItem: Kirigami.Avatar { ..... }
}
```
This complains about uninitialized properties in `Kirigami.Avatar`. (`id`, `currentRoom`, `avatar`, `index` are properties utilized during run time)
After we get around these two issue, this MR will be ready from my side.
QDesktopServices::openUrl does not have XDG activation support yet so it can't raise an existing browser window when opening URLs
Instead use KIO::OpenUrlJob, which does support that
It's an optional part of syntax-highlighting so just searching for
the it is not enough we need to make sure to have the qml module.
Also don't link to it, we only need it at runtime.
Adds support for xdg_activation_v1 when calling the application from the
system tray by using KStatusNotifier which supports it.
Listens to XDG_ACTIVATION_TOKEN as it's passed when we are started from
dbus.
The filter callback is called very often (O(messages)). The current
filter model shows some significant overhead in QML internals. Moving
that to C++ makes it quite a bit faster.