Makes setting yt-dlp's `format` field easier by giving it its own documented plugin.
Old:
```
my_format_preset:
ytdl_options:
format: "best"
```
New:
```
my_format_preset:
format: "best"
```
The old method will still work, so do not worry about updating configs ASAP. However, the option is available to save a few lines 😉
* [BUGFIX] Fix missing contains function when checking entries
* remove children func
* [BACKEND] Bandcamp e2e test, update music example
* WIP
* combine soundcloud and all music into music_audio config
* sc fixtures
* updated tests and examples
* bandcamp e2e test
* regen off
* remove url validators
* use bandcamp artist url for more parent coverage
* lint
