Store angle::Format in gl::VertexAttribute. Instead of storing type/size/normalized/pureInteger we instead store a pointer to the angle::Format. This makes some code logic simpler and will let us more easily check if a vertex attribute format changes in calls to VertexAttribPointer or VertexAttribFormat. This CL adds extra information to angle::Format to represent the vertex format info needed. It also caches the channel count so that it can be queried faster. Also renames "Int" -> "Sint" in UtilsVk for consistency. Bug: angleproject:3256 Change-Id: I5ef9b983dad8a58c341113c802500b89ce081566 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1684293 Commit-Queue: Jamie Madill <jmadill@chromium.org> Reviewed-by: Jonah Ryan-Davis <jonahr@google.com>