[graphite] Store DepthStencilSettings on ShaderInfo

In the long term, RenderStep will only store its StencilSettings and
it will have flags that control how the depth test/write state are
set in combination with drawpass-level requirements.

Bug: 500416105
Change-Id: I73a57ee3ca4ceab78b6415bdecee87092a56d423
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/1374016
Commit-Queue: Michael Ludwig <michaelludwig@google.com>
Reviewed-by: Thomas Smith <thomsmit@google.com>