New Cover Downloader
- Downloads covers async
- generates Thumbnails using image crate
- checks widget hidpi scale when picking a thumbnail #196
- Locked Cache of gdk::Texture
- Major improvement of performance and startup speed on mobile
- Fix of an old TODO: Player.rs can now fetch the MPRIS cover in async when it isn't downloaded yet when starting playback.
- fixed some warning (unused imports) printed by newer rust versions, so this build doesn't print warnings.
This is based on @alatiera's new cover downloader !286 , but drops the FileMonitors and lock files for tokio::sleep and adds Thumbnail generation.
Feel free to squash commits when merging.