Revert "Rename GrStencilAttachment class to generic GrAttachment"

This reverts commit 6113d50ec48be049c13a6e4bbea191df93e68674.

Reason for revert: Breaking MSAN bot

Original change's description:
> Rename GrStencilAttachment class to generic GrAttachment
>
> Additional this adds a UsageFlags member to the new GrAttachment
> class.
>
> Bug: skia:10727
> Change-Id: Ifc0bfffd959f5fbc46bfcdf269e1b2a933929753
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/323107
> Commit-Queue: Greg Daniel <egdaniel@google.com>
> Reviewed-by: Brian Salomon <bsalomon@google.com>

TBR=egdaniel@google.com,bsalomon@google.com,csmartdalton@google.com

Change-Id: I2ee2a1fcabd75bc24d3b7c3f76d971a3adb370a3
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: skia:10727
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/324276
Reviewed-by: Jim Van Verth <jvanverth@google.com>
Commit-Queue: Greg Daniel <egdaniel@google.com>
65 files changed