Rename SkImageSource to SkImageImageFilter

Also deletes the unnecessary old header file.

Bug: skia:11230
Change-Id: Ie7c3926fe635a37e617e5e1fcac7c05eb576bbf1
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/368617
Reviewed-by: Robert Phillips <robertphillips@google.com>
7 files changed