Moving all unicode work into SkUnicode

Change-Id: Ia8983a949e8a92b3562e2c7377cae545b5592ff1
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/567556
Reviewed-by: Ben Wagner <bungeman@google.com>
Commit-Queue: Julia Lavrova <jlavrova@google.com>
14 files changed