Bind D3D constants.

Final step to get shader constants working. Changes the root
signature to store the constant buffer view directly inside it, and
sets it via the command list.

Change-Id: Ib82a5cc60dd54347f2c5b6885f3ef553e005e760
Bug: skia:9935
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/293348
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Jim Van Verth <jvanverth@google.com>
7 files changed