[AIRFLOW-3569] Add "Trigger DAG" button in DAG page (/www only) (#4373)
[AIRFLOW-3569] Add "Trigger DAG" button in DAG page (/www only) (#4373)

This is a back-ported version of the change introducted to the RBAC ui
in #4373.

owlabs/incubator-airflow,owlabs/incubator-airflow,owlabs/incubator-airflow,owlabs/incubator-airflow