Remove GrFragmentProcessor::addCoordTransform()

At this point, every created instance of GrCoordTransform is an identity
so can be removed. Adding it manually using addCoordTransforms() is no
different than relying on the (current) implicitly returned coord
transform if the FP calls setUsesSampleCoordsDirectly().

Removing the addCoordTransform() lets us enforce that this remains the
case and this CL also deletes all of those members that were previously
used to provide access to the sample coordinates.

As part of this, GrFragmentProcessor.h and many other files no longer
need to include GrCoordTransform.h. This exposed a surprising popularity on
SkMatrixPriv.h so I updated those files to include that header directly.

Technically, a .fp file can still have an @coordTransform section and
the sksl generator will try and call addCoordTransform, which will then
fail to build. A follow up CL removes that support in .fp generation.

Bug: skia:10416
Change-Id: I5e4d2bb49ee6d7e56ac75ca00be5631106fec20b
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/299291
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Michael Ludwig <michaelludwig@google.com>
65 files changed