Pure Haskell implementation of `base:GHC.Unicode`.

Switch to a pure Haskell implementation of base:GHC.Unicode, based on the implementation of unicode-data.

• Remove cbits and corresponding generator.
• Add a generator for Unicode property files. This generator can actually produce more data; all but the relevant properties are commented out. The generated files are located in GHC.Unicode.Internal sub-modules.
• Update GHC.Unicode.
• Add test unicode003 to check general categories and case mappings for all characters.
• Add Python scripts to compare GHC outputs to another language.

Fixes #21375 (closed)

Please take a few moments to verify that your commits fulfill the following:

• are either individually buildable or squashed
• have commit messages which describe what they do (referring to Notes and tickets using #NNNN syntax when appropriate)
• have added source comments describing your change. For larger changes you likely should add a Note and cross-reference it from the relevant places.
• add a testcase to the testsuite.
• if your MR affects library interfaces (e.g. changes base) or affects whether GHC will accept user-written code, please add the ~"user facing" label.
• updates the users guide if applicable
• mentions new features in the release notes for the next release