Add SkArc

Nothing fancy, just a more convenient container for the four parameters
to drawArc. Ganesh already had this (so I replaced it), and with an
incoming isArc API, it's helpful to have a single struct to hold it all.

Bug: b/330506337
Change-Id: I3fb25b8cc9d50f4b2f1d281452e87a07aaca2c00
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/842239
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: Greg Daniel <egdaniel@google.com>
8 files changed