CL/Vulkan: Setup a dispatch loop per commandqueue Commands submitted to renderer need clean up ops post completion. Setup a background thread per commandqueue that waits on the command completion and performs the post completion operations. Updated test suite and `angle.json` was autogenerated with `scripts/run_code_generation.py`. Bug: angleproject:375231041 Change-Id: I82b4211ee6e229c679ef31897fc63d61fa904bb5 Signed-off-by: Gowtham Tammana <g.tammana@samsung.com> Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/5960590 Reviewed-by: Austin Annestrand <a.annestrand@samsung.com> Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org> Reviewed-by: Cody Northrop <cnorthrop@google.com> Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org> Reviewed-by: Yuly Novikov <ynovikov@chromium.org>