Implement BaseVertex draw calls for Vulkan, OpenGL, NULL contexts. This adds support for the following functions: - glDrawElementsBaseVertex - glDrawRangeElementsBaseVertex - glDrawElementsInstancedBaseVertex Bug: angleproject:3582 Bug: angleproject:3402 Bug: angleproject:4166 Change-Id: I83770f62e3a918c0965fd4ca8c7d9e598b8b4154 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1929083 Commit-Queue: Jamie Madill <jmadill@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org>