Revert "Migrate metal tools away from GrContext"

This reverts commit 3eb813e0cc134767a10e9efd4811fc519eccb280.

Reason for revert: Broke iOS

Original change's description:
> Migrate metal tools away from GrContext
> 
> Change-Id: I73a73ca5d088c35acd23be3336d8d1e3e859a82e
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/318760
> Commit-Queue: Brian Salomon <bsalomon@google.com>
> Auto-Submit: Adlai Holler <adlai@google.com>
> Reviewed-by: Brian Salomon <bsalomon@google.com>

TBR=bsalomon@google.com,robertphillips@google.com,adlai@google.com

Change-Id: Idf74c936cfe8481e18455dcc0faa21155884b198
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/319017
Reviewed-by: Adlai Holler <adlai@google.com>
Commit-Queue: Adlai Holler <adlai@google.com>
5 files changed