* Avalonia: Another Cleanup
This PR is a cleanup to the avalonia code recently added:
- Some XAML file are autoformatted like a previous PR.
- Dlc is renamed to DownloadableContent (Locale exclude).
- DownloadableContentManagerWindow is a bit improved (Fixes#3491).
- Some nits here and there.
* Fix GTK
* Remove AttachDebugDevTools
* Fix last warning
* Fix JSON fields
