.NET: `\p{LC}` doesn't work, `.` and `\w` doesn't properly support Unicode

[Aloso]

All identified problems (most have been addressed in Pomsky 0.10):

• .NET doesn't support code points (in hexadecimal notation) outside the BMP – must be converted to two UTF-16 surrogates
  • make it work in string literals (e.g. '𐌰')
  • make it work for hexadecimal code points above U+FFFF (e.g. U+10330) instead of producing an error
• .NET doesn't support arbitrary code points (. or C) outside the BMP #89
• \pL as shorthand for \p{L} doesn't work
• \p{LC} doesn't work
  • polyfill?
• scripts and boolean properties don't work at all
• needs investigation to see if all blocks are supported
• check if block names are correctly normalized: underscores must be removed, but dashes preserved
• \v and \h aren't supported
• .NET: \w (and by extension \b and \B) don't conform to Unicode #88
• need to check if backreferences like \80 are too high (doc)
• any further bugs may surface during fuzzing

To Reproduce

The regex-test crate should be was expanded to run .NET tests and run in CI (currently only on Ubuntu).

Expected behavior

.NET flavor works reliably, using unsupported features produces an error.