Add validation for ObjectLabel The validation of ObjectLabel is empty. Move the validation in ValidateObjectLabelKHR to a new ValidateObjectLabelBase (except the extension check), and make ValidateObjectLabel and ValidateObjectLabelKHR both call ValidateObjectLabelBase after the version/extension check. An end2end test is added Bug: angleproject:360903471 Change-Id: Iabfd3c16c5423b2ab2fe5e417fe75eed00237c92 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/5919129 Reviewed-by: Amirali Abdolrashidi <abdolrashidi@google.com> Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org> Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>