feat(ci): add lint-actions step to build.yaml (#5957)

* feat(ci): add lint-actions step to build.yaml

This adds a new job to the Build CI pipeline to lint our GitHub Actions.

By doing this, we can prevent typos from slipping in.

Fixes #5776

* fix: disable shellcheck in actionlint

I don't think we want to enable this for now.

* fix: ignore set-output warnings for now

It's deprecated but there isn't a reason to move away from using it yet.