use sk_sp<SkStrike> instead of SkStrikeSpec

This CL focuses on removing the SkStrikeSpec from the GlyphVector.
Now the GlyphVector can use an SkStrike directly. This CL
is mostly a bunch of tricky plumbing.

Change-Id: I4eb8ccfc44d9e8b7f35578bf754c188a7fd55596
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/469176
Reviewed-by: Ben Wagner <bungeman@google.com>
Commit-Queue: Herb Derby <herb@google.com>
7 files changed