Allow specifying tag for listener for api_permission purposes

Allow specifying tag for listener for api_permission purposes

This commit will allow adding tag to http listeners:

listener:
  - port: 4000
  - module: ejabberd_http
  - tag: "magic_listener"

that later can be used to have special api_permission just for it:

api_permissions:
  "magic_access":
    from:
      - tag: "magic_listener"
    who: all
    what: "*"