D3D11: implement image load/store for non-compute shaders. Output image metadata and image2d replacement string in other shader types. Implement the actual HLSL transform for fragment shaders. Re-enable problematic test. Bug: angleproject:7121 Change-Id: I49b815695757e822e6fdfe599e07ceb5b1d6a75c Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/3550544 Reviewed-by: Jamie Madill <jmadill@chromium.org> Commit-Queue: Stephen White <senorblanco@chromium.org> Reviewed-by: Geoff Lang <geofflang@chromium.org>