lots of sRGB and F16 blits

- generalize F16 xfermode procs
- spriteblits for F16 and sRGB
- saveLayer now respects colortype and profiletype

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1686013002

Review URL: https://codereview.chromium.org/1685203002
17 files changed