Stop using hb_script_t in the minikin methods

HarfBuzz started converting Hant/Hans to Hani in
hb_script_from_iso15924_tag. Minikin needs to distinguish them
for simplified/traditional/Japanese Han characters.
So, changing minikin methods to take raw script TAG instead of
hb_script_t enum.

Bug: 204812473
Test: minikin_tests
Change-Id: If90ec7636fcd37a8ea2b8aa672744dad1300e43e
4 files changed