Use regexp_property_values gem for accurate property mapping

[tom-lord]

Replace usage of the unicode ranges pstore (which had not been updated for unicode 13.0 --> 15.1+!), with the regexp_property_values gem.

The gem hooks into the C API to directly load the matching codepoints for named properties. It's something. wanted to do originally with this library, 10+ years ago, but didn't know how back then! 😄

Thanks to @jaynetics for pointing this out, and building the above gem.

This PR solves the long-standing issue: #14

It fixes several related issues:

• Some named properties did not generate any examples, e.g. /\p{Carian}/. This was because the script to generate (by brute force!) any matching characters only searched up to 0xFFFF, but the only matching characters start higher than this, from 0x102A0: "𐊠𐊡𐊢𐊣𐊤𐊥𐊦𐊧𐊨𐊩..."
• The gem previously only stored a maximum of 128 characters per property, for performance reasons, which meant not all possible matching characters would be included in examples. This limitation is no longer present.
• Some named properties may have been missing entirely, e.g. Age=15.1, or overlooked in the original script, e.g. \p{In Miscellaneous Mathematical Symbols-B}. Not any more, because it's directly calling the Onigmo API.
• The gem now correctly handles property names padded with hyphens or spaces.

---

Examples:

/\p{Age=6.0}/.random_example #=> "䧖"
/\p{In Miscellaneous Mathematical Symbols-B}/.random_example #=> "⦉"
/\p{Lowercase-Letter}/.examples(max_group_results:99999).count
=> 2155