[canvaskit] Add drawVertices API

This also does some clean up to how we name enums - the caps felt a bit
obnoxious. CAPS are reserved now for constants (like colors).

Small bug fix with leaking memory on discrete path effects

This also adds a few more things from PathKit

Bug: skia:
Change-Id: Iad7e21ac36d35a36a8b255dc82b1dcc886344db1
Reviewed-on: https://skia-review.googlesource.com/c/166804
Commit-Queue: Kevin Lubick <kjlubick@google.com>
Reviewed-by: Mike Reed <reed@google.com>
8 files changed