add support for specifying FAB roles (airflow.userRoles) #282
Description
Currently, if a user wants to add roles beyond the default (Public, Viewer, User, Op, Admin), they must use a manual method like the UI or CLI.
We should add a new value like airflow.roles (along with: airflow.rolesUpdate, airflow.rolesTemplates), which allows users to declaritvly add new FAB roles.
See the docs for Access Control in airflow.