Read Unicode property UnicodeSet data from ICU4C

[echeran]

Instead of continuing to parse the PPUCD file directly and fix logic / perf issues (ex: #454), we want to replace that approach with directly reading UnicodeSet data for Unicode properties directly from ICU4C.

This will match the work for reading CodePointTrie data (#132) (as described in dupe issue #508).

[sffc]

Possible duplicate of #578