Update SkMesh buffer API to take const void* instead of SkData

Also expose a size() function on the public IB and VB types.

Bug: skia:12720
Change-Id: Ibeccf6d2d6ba411e9e77be582d0cb1622bc76ccd
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/555005
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
5 files changed