Extending SkParagraph API for client-provided unicode

Change-Id: Ic9264720102bc415c9d12d0e40e16443ac483c61
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/573499
Reviewed-by: Kevin Lubick <kjlubick@google.com>
Commit-Queue: Julia Lavrova <jlavrova@google.com>
14 files changed