D3D11: implement EXT_clip_control This implements EXT_clip_control for the D3D11 renderer, so that I can use a reversed-Z depth buffer with ANGLE. Tested with angle_deqp_gles2_tests.exe --deqp-egl-display-type=angle-d3d11 --deqp-case=dEQP-GLES2.functional.clip_control.* and angle_end2end_tests.exe --gtest_filter=*D3D11* Bug: angleproject:6554 Change-Id: I1d11cd04a6654c28530b11104470f0cad0009abe Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/3218659 Reviewed-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Geoff Lang <geofflang@chromium.org> Commit-Queue: Jamie Madill <jmadill@chromium.org>