Fix String.toLowerCase and toUpperCase.

Rather than try to cope with Lithuanian, let's just hand that one to ICU4C.
I've removed my hand-crafted Azeri/Turkish lowercasing too, in favor of ICU.
Presence of a high surrogate (which implies a supplemental character) is a
good reason to hand over to ICU too.

On the uppercasing side, I've kept our existing hard-coded table and just
added code to defer to ICU for Azeri, Lithuanian, and Turkish (plus
supplemental characters). I don't like the tables, but I don't have proof
that they're incorrect.

Bug: 2340628
Change-Id: I36b556b0444623a5aacc1afc58ebb4d84211d3dc
7 files changed