- add api docs helpers

- allow multiple HTTP methods on the same endpoint

- multiple values for route and methods

  > keep the same in the ui for now, later own we can imagine a
  > multi-value selection or just add text field w/ proper validation
  > and cleanup
  >
  > remove the route field in the table of endpoint_route
  >
  > support a comma separated list of routes maybe support comma
  > separated list of methods use only routing.routes for generating the
  > rule sort and freeze its values to update the endpoint hash
  >
  > catch dup route exception on the sync to detect duplicated routes
  > and use the endpoint_hash to retrieve the real record (note: we
  > could store more info in the routing information which will stay in
  > the map)
  >
  > for customizing the rule behavior the endpoint the hook is to
  > override the registry lookup
  >
  > make EndpointRule class overridable on the registry

NOTE in v16 we won't care anymore about odoo controller so the lookup of
the controller can be simplified to a basic py obj that holds the
routing info.
