Use the forget function to leave a room everywhere this is both for consistency and to reduce dependencies. This way no dependency on RoomManager is required to leave a room and since in all cases they have an object they can just call the function.
Remove any dependencies on App from the spaces module. This requires moving some dialogs either to spaces, or libneochat if they're used more generically.
First of all, these are now all separate dialogs instead of shoving all
of these functions (which are only marginally related) into one single
dialog. We also convert these to in-app Kirigami Dialogs, which look a
bit nicer. I also touched up the UX in some places, such as adding
descriptions which were previously available to translators. I also hid
some not oft used options like setting a topic, which almost nobody does
before creating a room/space.
