Add SkImageFilters::Blend rename for Xfermode filter

This better matches SkShaders::Blend and SkColorFilters::Blend factories.

Bug: skia:9310
Change-Id: I02a3fe488a446b803df96518caacff1fdf536e9f
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/324623
Commit-Queue: Michael Ludwig <michaelludwig@google.com>
Reviewed-by: Florin Malita <fmalita@chromium.org>
15 files changed