Reland "Hook up ShaderErrorHandler in the Metal backend."

This reverts commit 0758da2c60b06d8c69baecc8fd049e84821fd31c.

Reason for revert: A different CL was causing the iOS failures

Original change's description:
> Revert "Hook up ShaderErrorHandler in the Metal backend."
>
> This reverts commit 69df532a55b97c3f95e9322929cf11e5d9c5d5fb.
>
> Reason for revert: See if this is causing the iOS redness on our tree
>
> Original change's description:
> > Hook up ShaderErrorHandler in the Metal backend.
> >
> > Also cleans up dumping of shader code to use GrShaderUtils.
> >
> > Change-Id: I4d2a13e1a54284d7da0242b74cebb3900921fc35
> > Reviewed-on: https://skia-review.googlesource.com/c/skia/+/337077
> > Commit-Queue: Jim Van Verth <jvanverth@google.com>
> > Reviewed-by: Brian Osman <brianosman@google.com>
>
> TBR=jvanverth@google.com,brianosman@google.com
>
> Change-Id: I34125bd560cfbd12e50c732137cf921067457be2
> No-Presubmit: true
> No-Tree-Checks: true
> No-Try: true
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/337184
> Reviewed-by: Robert Phillips <robertphillips@google.com>
> Commit-Queue: Robert Phillips <robertphillips@google.com>

TBR=jvanverth@google.com,robertphillips@google.com,brianosman@google.com

# Not skipping CQ checks because this is a reland.

Change-Id: I46c9d4356702b44c75bb416ae6e8639c7b23b63c
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/337187
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
7 files changed