add drawString to ease the pain of converting to skfont

Bug: skia:
Change-Id: I88418f87883b66204427fbdab471e74c78835ac4
Reviewed-on: https://skia-review.googlesource.com/c/181407
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Mike Reed <reed@google.com>
Auto-Submit: Mike Reed <reed@google.com>
10 files changed