feat(transformer): RegexpFlags

[magic-akari]

I use a different strategy than Babel. (but same with swc)
I converted unsupported Regexp flags into RegExp constructors so they can be polyfilled by users.

[codspeed-hq]

CodSpeed Performance Report

Merging #977 will not alter performance

_{Comparing magic-akari:regex (4fcd129) with main (d5fb3d4)}

Summary

✅ 22 untouched benchmarks

[mysteryven]

Learn a lot from this implementation!