fix(kong): add RBAC rules for listing namespaces when gateway API is detected

[pmalek]

What this PR does / why we need it:

This adds RBAC rules for listing namespaces. There's not way to detect if user has objects from particular API group present in the cluster so this can only be conditional on the presence of Gateway API CRDs in the cluster.

This could potentially be added (by refactoring) to

charts/charts/kong/templates/controller-rbac-resources.yaml

Lines 10 to 18 in 72650f5

	- apiGroups:
	- ""
	resources:
	- configmaps
	- pods
	- secrets
	- namespaces
	verbs:
	- get

but KIC doesn't need to list namespaces when users do not use Gateway API (and specifically namespace selectors).

Related controller-runtime issue describing why we need those permissions: kubernetes-sigs/controller-runtime#1156

Which issue this PR fixes

Fixes #790

Special notes for your reviewer:

Checklist

[Place an '[x]' (no spaces) in all applicable fields. Please remove unrelated fields.]

• PR is based off the current tip of the main branch.
• Changes are documented under the "Unreleased" header in CHANGELOG.md
• New or modified sections of values.yaml are documented in the README.md
• Commits follow the Kong commit message guidelines