[FE] Implementation of Metrics RBAC UI

FB:https://github.com/Percona-Lab/pmm-submodules/pull/2949#issuecomment-1385208940

When running the app add the ENABLE_RBAC=1 env variable.

A new section should appear in the configuration - Access Roles. Where you can add/edit/delete user roles. For assigning user roles use the Users tab, there's an additional column for assigning roles to users.

Default role is assigned to new users.

On the Add/Edit pages you can assign the metrics access - it's the same as in the Explore page.