Image filters: implement SkImage::makeWithFilter().

This API provides a way to directly filter a subregion of an SkImage
(usually texture-backed), and returns an SkImage which may include
extra padding, along with a size to indicate the active region.

GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1964043002

Review-Url: https://codereview.chromium.org/1964043002
5 files changed