Add SkSpecialImage::makeTextureImage entry point

This is calved off of: https://codereview.chromium.org/1785643003 (Switch SkBlurImageFilter over to new onFilterImage interface)

GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1813813002

Review URL: https://codereview.chromium.org/1813813002
4 files changed