Add custom annotations into GatewayClass and NginxGateway manifests

[sgavrylenko]

Proposed changes

Add custom annotations for GatewayClass and NginxGateway objects.
It can be useful in different cases

Problem: For deploying of our service we use ArgoCD. For this we have a Helm Chart that contains multiple resources that are using CRDs, that are not managed by this helm chart. When trying to sync this application, it fails if at least one CRD is not installed in the cluster. This is expected.

Solution: To work around this problem, we want to use SkipDryRunOnMissingResource option as annotation for GatewayClass and NginxGateway objects from the nginx-gateway-fabric chart

Testing: Helm template works fine

Checklist

Before creating a PR, run through this checklist and mark each as complete.

• I have read the CONTRIBUTING doc
• I have added tests that prove my fix is effective or that my feature works
• I have checked that all unit tests pass after adding my changes
• I have updated necessary documentation
• I have rebased my branch onto main
• I will ensure my PR is targeting the main branch and pulling from my branch from my own fork

Release notes

If this PR introduces a change that affects users and needs to be mentioned in the release notes,
please add a brief note that summarizes the change.

[sgavrylenko]

Actually, do we really need GatewayClass and NginxGateway objects during the installation of operator? Can we mark them as optional and create only when we need it?

[sjberman]

@sgavrylenko Thanks for the submission. Right now we do require the NginxGateway resource because we bootstrap NGF based on its contents (right now just one field, but could expand in the future).

GatewayClass though may not be necessary. Worth a discussion amongst the team at least.