Revert "Rm readPixels from GrSurface & move read/writeSurfacePixels to GrContextPriv"

This reverts commit fb0bd98a43fa11e09705837418167dd72bb4a361.

Reason for revert: ANGLE failures

Original change's description:
> Rm readPixels from GrSurface & move read/writeSurfacePixels to GrContextPriv
> 
> This is in service of: https://skia-review.googlesource.com/c/11125/ (Add parallel proxyID to StencilOps & RenderTargetOpList) where I want a better choke point for texture creation to improve discard handling.
> 
> Change-Id: If57a7de47edc0853dae7bc61337d9acdc03d63b0
> Reviewed-on: https://skia-review.googlesource.com/11200
> Reviewed-by: Brian Salomon <bsalomon@google.com>
> Commit-Queue: Robert Phillips <robertphillips@google.com>
> 

TBR=bsalomon@google.com,robertphillips@google.com,reviews@skia.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

Change-Id: I7241070dc1f9df47181061e07adab141f9857974
Reviewed-on: https://skia-review.googlesource.com/11324
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
29 files changed