Use Microsoft's ComPtr to wrap D3D12 objects.

Change-Id: I4bd173428a2b65f0bc1994fb794ef9d4d68d5ba0
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/314957
Reviewed-by: Brian Salomon <bsalomon@google.com>
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Jim Van Verth <jvanverth@google.com>
28 files changed