[Feature Request] Optional Unicode Category

[soasme]

Is your feature request related to a problem? Please describe.
In some cases, embedding range pattern tables load a lot of data into memory and it's unnecessary.
It's up to the user to decide whether to enable range patterns.

Describe the solution you'd like
Add a new macro: ENABLE_UNISTR.
If it's enabled, peppapeg will load unicode categories from libunistring, otherwise, [\p{..}] only supports some built-in categories.

Describe alternatives you've considered
N/A

Additional context

• https://www.gnu.org/software/libunistring/manual/libunistring.html#General-category
• https://unicode.org/reports/tr31/
• https://en.wikipedia.org/wiki/Template:General_Category_(Unicode)

[soasme]

See #99