kuberay-apiserver should match kuberay-operator in watchNamespaces feature

[shaoqin2]

kuberay-helm/helm-chart/kuberay-operator/values.yaml

Lines 76 to 79 in 07463a1

	# The KubeRay operator will watch the custom resources in the namespaces listed in the "watchNamespace" parameter.
	# watchNamespace:
	# - n1
	# - n2

This is a very useful feature installing the operator, but kuberay-apiserver does not match this behavior when using singleNamespaceInstall.

If we install apiserver, operator in namespace X and operator with watchNamespac [X, Y], trying to manage CRD in Y, the setup leads to

2023/11/22 16:56:17 could not list clusters rpc error: code = Unknown desc = List clusters failed.: List RayCluster failed in tsray: rayclusters.ray.io is forbidden: User "system:serviceaccount:default:kuberay-apiserver" cannot list resource "rayclusters" in API group "ray.io" in the namespace "Y"

Should we consider also installing the RBAC for CRD in kuberay-apiserver to a list of watchNamespace like kuberay-operator?

I'm happy to provide that PR if maintainers believe this is a reasonable request