Remove support for copyAsDraw in gpu copySurface.

The major changes on a higher lever are:
1) The majority of all copies now go through GrSurfaceProxy::Copy which
takes in a proxy and returns a new one with the data copied to it. This
is the most common use case within Ganesh.

2) The backend copy calls no longer do draws, require origins to be the
same, and won't do any swizzling or adjustment of subrects. They are
all implemented to be dumb copy this data to this other spot.

3) The GrSurfaceContext copy call has now been moved to priv and renamed
copyNoDraw, and a new priv copyAsDraw was added to GrRenderTargetContext.

4) WritePixels and ReplaceRenderTarget both need to specifiy the destination
of copies. They are the only users (besides the GrSurfaceProxy::Copy) which
call the priv methods on GrSurfaceContext.

Change-Id: Iaf1eb3a73ccaf39a75af77e281dae594f809186f
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/217459
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Greg Daniel <egdaniel@google.com>
60 files changed