Generate Signed Distance Field directly from vector path

Generate Signed Distance Field directly from vector path

Add SkGenerateDistanceFieldFromPath API to generate signed distance field directly from SkPath.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1643143002

Committed: https://skia.googlesource.com/skia/+/4de97a64e8829323a7070b623411d9f9ddb0cd0f
Committed: https://skia.googlesource.com/skia/+/e8f0a7b986f1e5583c9bc162efcdd92fd6430549
Committed: https://skia.googlesource.com/skia/+/67c7c81a82b6351e9fbbf235084d7120162d9268
Review-Url: https://codereview.chromium.org/1643143002
Committed: https://skia.googlesource.com/skia/+/64b70b096ac20833d9737758a4bd5f2a51078bc4
Review-Url: https://codereview.chromium.org/1643143002