Remove most GrCoordTransform code

All coord transforms were identity, so this enshrines that
knowledge, then transitively removes a large amount of code.

Bug: skia:10416
Change-Id: Iae4af9ca21590bced1ce9fce3ab807f6cceaebd4
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/300234
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
49 files changed