[Feature Request] Add loop modes to slicerT

Nobody has claimed this yet.

### Enhancement Summary

Add loop modes to slicerT similar to the ones in AFP
loop modes determine the behavior of slicerT when a slice finishes being played
here is my suggestion for what modes should be implemented (they are identical to AFP's modes except for the last one):
- disabled: when a slice finishes playing it stops producing sound
- loop: when a slice finishes playing it replays again until the note ends
- mirror: when a slice finishes playing a reversed version of it plays, when that version finishes a normal version plays and so on
- continue: when a slice finishes playing it automatically plays the next slice as it was a normal sample and not sliced

### Implementation Details / Mockup

I don't currently have a mockup but it should be implemented similar to how it's implemented in AFP
four buttons. only one can be activated at a time. it affects all the slices
i think there's a lack of space issue that can be fixed by making that top preview panel shorter

### Please search the issue tracker for existing feature requests before submitting your own.

- [X] I have searched all existing issues and confirmed that this is not a duplicate.

Start by locating slicerT and comparing its implementation with AFP, which the issue identifies as the model for these modes. Define how the four mutually exclusive modes affect all slices and how the interface fits the available space; done means each mode has the described playback behavior.

Written by the indexing model from the issue text.