Give list mods ability to overwrite GD level_id after adding demons #283
Description
Currently, when adding new demons, the frontend makes specifying the GD level id of the level mandatory (the backend has no such stipulations though). However, after the demon is added, it cannot be changed again via the API (PATCH /demons/ doesn't even support a level_id field). We should fix that up:
- Make level id optional when adding demons on the frontend as well (was done in Fix code
500when adding a demon with level ID #203) - Allow PATCH /demons/ to change level_ids
- Give frontend interface for changing level IDs