Autogen format table and internal shaders for Metal.

Bug: angleproject:2634
Change-Id: I4d81fcd17a0e9959ba9c38a250acc7abb168f54c
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1855067
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>