In the 'extraroute-atomic' api-def as it was first merged 
some router member actions (PUT add/remove_extraroutes) were defined
in one api-def (extraroute_atomic.py), while others
(PUT add/remove_router_interface) were defined in another (l3.py).
This (in the subsequent neutron implementation change ) broke
This test sent POST/GET /v2.0/routers/router-id/add_router_interface,
and expected response 405 Method Not Allowed. Due to the split
definition it actually received 404 Not Found. In the meanwhile all
four PUT member actions were working properly.
This change sets the 'extraroute-atomic' api-def's ACTION_MAP to contain
the member actions of both the 'router' and the 'extraroute-atomic'
extensions' member actions in order to get all four member actions
Partial-Bug: #1826396 (rfe)
Related-Change: https://review.opendev.org/655680 (spec)