Vulkan: Binding available buffer range to descriptor. This is fully conformant with GLES including robustness, where robustness specifically allows returning any values in the buffer. The goal is to eventually remove all shader-variable-specific info out of the descriptor set update. This will let us fix cache bugs that pop up when we move the descriptor set cache to the share group. Bug: angleproject:6776 Change-Id: Iccef33ca6174a68e359a07dc957a276b2484f97f Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/3431725 Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org> Reviewed-by: Yuxin Hu <yuxinhu@google.com> Commit-Queue: Jamie Madill <jmadill@chromium.org>