Feature Request: Allowing Bulgarian Cyrillic Script to be enabled with stylistic set (currently only locl can enable this feature)

[jothefiredragon]

Description of the new feature/enhancement (with images if possible)

Like Cascadia Code contains glyphs for Russian Cyrillic, Bulgarian Cyrillic and Serbian Cyrillic. However only the former two can be activated without requiring locl feature. Since it's been pointed out here #634 (comment) that usage of such feature can be inconvenient, it would be appropriate to enable Bulgarian Cyrillic glyphs via stylistic sets as well.

Thank you very much in advance for your consideration.

Proposed technical implementation details (optional)

[jothefiredragon]

I just found out about this tool written in Python that solves this issue. https://github.com/twardoch/fonttools-opentype-feature-freezer/ I still wish that such problem can be dealt with without the help of this tool though.