Validate TLS Secrets

[pleshakov]

Is your feature request related to a problem? Please describe.
NKG doesn't validate the contents of a TLS Secret used for TLS termination of a Listener. As a result, an invalid cert or key might end up referenced in the generated NGINX config, which will make NGINX fail to reload.

Describe the solution you'd like
Ensure that an invalid TLS Secret cannot make NGINX fail to reload. Report the validation errors in the Gateway resource status.

Describe alternatives you've considered

Additional context

Aha! Link: https://nginx.aha.io/features/NKG-24

[mpstefan]

We believe this is already implemented.