Rename SkBitmapProcStateAutoMapper methods

x(),y() -> fractionalIntX(), fractionalIntY()

(to clarify the return type)

Also add fixed & int helpers.

R=reed@google.com
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1666433003
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Review URL: https://codereview.chromium.org/1666433003
8 files changed