CL/VK: Add ArgumentWorkgroup handling Each OpenCL kernel can have ArgumentWorkgroup args - which are treated as spec constants. Bug: angleproject:366415134 Change-Id: I2761010610e5b991e959006e7b78f1241a687960 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/5860304 Commit-Queue: Austin Annestrand <a.annestrand@samsung.com> Reviewed-by: Geoff Lang <geofflang@chromium.org> Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>