add static factories for SkPath

Bug: skia:9000
Change-Id: I474d512cafd79d7c74b42ee86cb34c039fd960b1
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/307458
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Mike Reed <reed@google.com>
7 files changed