Add lint to the API repo

If you introduce curly unicode quotes (““ instead of ""), you will eventually break the linter on istio.io.

For example https://github.com/istio/api/pull/3426

> // For text format, the output of the empty operator is changed from “-“ to an empty string.

leads to https://github.com/istio/istio.io/pull/16281 ([prow](https://prow.istio.io/view/gs/istio-prow/pr-logs/pull/istio_istio.io/16281/lint_istio.io/1896743955798691840))

>./content/en/docs/reference/config/istio.mesh.v1alpha1/index.html:1707:For text format, the output of the empty operator is changed from “-“ to an empty string.
> Ensure content only uses standard quotation marks and not “

Could we please introduce some light linting to PRs here for this use case, which has now happened at least enough times that i remember it?