Add `ENTERPRISE_SUPPORT_URL` variable.

CHANGELOG.md

 - Role: edxapp
+  - Added `ENTERPRISE_SUPPORT_URL` variable used by the LMS.
+
+- Role: edxapp
   - Added OAUTH_DELETE_EXPIRED to enable automatic deletion of edx-django-oauth2-provider grants, access tokens, and refresh tokens as they are consumed. This will not do a bulk delete of existing rows.
 
 - Role: mongo_3_2

playbooks/roles/edxapp/defaults/main.yml

@@ -728,6 +728,8 @@ EDXAPP_ENTERPRISE_COURSE_ENROLLMENT_AUDIT_MODES:
 
 EDXAPP_ENTERPRISE_ENROLLMENT_API_URL: "{{ EDXAPP_LMS_ROOT_URL }}/api/enrollment/v1/"
 
+EDXAPP_ENTERPRISE_SUPPORT_URL: ''
+
 # The assigned ICP license number for display in the platform footer
 EDXAPP_ICP_LICENSE: !!null
 
@@ -1201,6 +1203,7 @@ lms_env_config:
   PASSWORD_MIN_LENGTH: "{{ EDXAPP_PASSWORD_MIN_LENGTH }}"
   PASSWORD_MAX_LENGTH: "{{ EDXAPP_PASSWORD_MAX_LENGTH }}"
   ENTERPRISE_ENROLLMENT_API_URL: "{{ EDXAPP_ENTERPRISE_ENROLLMENT_API_URL }}"
+  ENTERPRISE_SUPPORT_URL: "{{ EDXAPP_ENTERPRISE_SUPPORT_URL }}"
   PARENTAL_CONSENT_AGE_LIMIT: "{{ EDXAPP_PARENTAL_CONSENT_AGE_LIMIT }}"
   ACE_ENABLED_CHANNELS: "{{ EDXAPP_ACE_ENABLED_CHANNELS }}"
   ACE_ENABLED_POLICIES: "{{ EDXAPP_ACE_ENABLED_POLICIES }}"