Use staging buffers in d3d for texture uploads.

Change-Id: I00a00e62dfb2021a2c380ef4217c1acec1f07672
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/303258
Commit-Queue: Greg Daniel <egdaniel@google.com>
Reviewed-by: Jim Van Verth <jvanverth@google.com>
7 files changed