If vertex array object binding is changed, we need to update
the pipeline cache with the attribute information of the newly
bound VAO. We cache the strides of attributes because emulated
attributes will have strides that don't match the stride info
cached in its binding struct. Also added a test case that
switches between multiple VAOs.

Bug: angleproject:4127
Test: angle_end2end_tests.exe --gtest_filter=SimpleStateChangeTestES31.MultipleVertexArrayObjectRendering
Change-Id: I4f23aec33d5aa5988baa41f3c63db5534daf75ca
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1917453Reviewed-by: Tobin Ehlis <tobine@google.com>
Commit-Queue: Tobin Ehlis <tobine@google.com>