Add Watch namespace support

[R1-lav]

Hello, I worked on a small PR that adds optional namespace scoping to the Temporal Worker Controller.

The controller can be restricted to a single namespace or a comma-separated
list of namespaces using the --watch-namespace flag or WATCH_NAMESPACE
environment variable.

When multiple namespaces are specified, the controller uses a multi-namespaced
cache and does not require cluster-wide watch permissions.

If unset, the controller preserves its existing cluster-wide behavior.

I also modified the rbac.yaml file to automatically create Roles instead of ClusterRoles when a specific key is set in the values (only usable when only one namespace is specified)

Tested on my side without any issue.

Could I create the pullRequest for review ?

Many thanks !

[carlydf]

Hi, please feel free to go ahead and set the PR. Off the bat, we think it would make more sense that, if someone is opting into namespace scope, we automatically switch to Roles instead of ClusterRoles instead of having a separate toggle. Will look at the PR once it's up!