Add CI checks for auto generated code.

[bpkroth]

Per discussions in #301, there are a few places where we auto-generate code.
It would be useful to have a check in the CI pipelines that these files have not been edited by hand and are up to date.

Can we automate this too? e.g. run it during the CI pipelines and make sure that no file changes are generated (e.g. with a git diff --porcelain check and abort the checkin since local changes are out of sync.

Originally posted by @bpkroth in #301 (comment)