Implement Sentakki editor

[LumpBloom7]

This implements the composer screen that will be used to compose Sentakki beatmaps. I've chosen to start over despite my previous attempt, as a lot of the code there is copied from osu!std, reducing my understanding and familiarity with the implementation.

osu doesn't really support custom ruleset editors at the moment(https://github.com/ppy/osu/issues/12612), but we can still work on them in the meantime.

Most of the basic functionality have been implemented, however there are still certain things that needs to be worked on.

Current problems

• Slides currently only support the manipulation of the first SlideBody
• • The idea is that every property within SentakkiSlideInfo could be freely adjustable at some point
• ~~https://github.com/ppy/osu/issues/11453~~
• ~~https://github.com/ppy/osu/issues/12630~~
• ~~Repositioning of hit objects are blocked when more than one blueprint is selected~~
• • ~~Unlike mania, the lanes of sentakki are circular... Maybe rotate all of them based on the drag origin.~~ resolved
• • ~~Touch notes should support simultaneous repositioning, but bounds checking is also not as simple as AABB. I'm currently thinking on a way to block movement based on distance to playfield centre.~~ resolved (Thanks @Flutterish!)
• LanedNotes currently disappear immediately instead of doing a fadeout similar to what std has.
• ~~HitExplosions for TouchNotes remain, even though they are hidden for LanedNotes.~~