Add looping option to SlicerT

[regulus79]

Problem

Currently, segments do not loop in SlicerT. This makes sense for many applications such as drums, but if you want to use SlicerT to make unique sounds by looping short segments, that is currently not possible.

Changes

• If looping is enabled, then when there are zero frames left in the note (notesLeft<=0), the note position is reset back to the start of the slice.
• A new LedCheckBox was added to the plugin interface to let the user toggle looping.
• loopEnable was added as a saveable/loadable setting.

This pull request partially addresses #7364

https://github.com/user-attachments/assets/34b44f1b-1fdf-4d3b-8d13-0ecb5b504ba2