Combine GrPerspQuad and GrQuad

Also moves GrQuadType to an inner enum of GrQuad as GrQuad::Type.
Renames some of the types for improved clarity (IMO)

Change-Id: I2c91d60374d2b7c414034e9fe0b0113a794bd610
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/216604
Commit-Queue: Michael Ludwig <michaelludwig@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
12 files changed