Adding SkUnicode tests

Change-Id: If85a2adebb4160a66f6aec394e3ec456be238867
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/659776
Reviewed-by: Ben Wagner <bungeman@google.com>
Commit-Queue: Julia Lavrova <jlavrova@google.com>
11 files changed