Allow configurable password reset support link.

CHANGELOG.md

 - Role: edxapp
   - Added the EDXAPP_ACTIVATION_EMAIL_SUPPORT_LINK URL with default value `''`.
+  - Added the EDXAPP_PASSWORD_RESET_SUPPORT_LINK URL with default value `''`.
 
 - Role: edxapp
   - Added the EDXAPP_SHOW_HEADER_LANGUAGE_SELECTOR feature flag with default value [false]

playbooks/roles/edxapp/defaults/main.yml

@@ -343,6 +343,7 @@ EDXAPP_MKTG_URL_LINK_MAP: {}
 EDXAPP_MKTG_URLS: {}
 EDXAPP_SUPPORT_SITE_LINK: ''
 EDXAPP_ACTIVATION_EMAIL_SUPPORT_LINK: ''
+EDXAPP_PASSWORD_RESET_SUPPORT_LINK: ''
 EDXAPP_EDXMKTG_USER_INFO_COOKIE_NAME: "edx-user-info"
 # Set this sets the url for static files
 # Override this var to use a CDN
@@ -962,6 +963,7 @@ generic_env_config:  &edxapp_generic_env
   MKTG_URLS: "{{ EDXAPP_MKTG_URLS }}"
   SUPPORT_SITE_LINK: "{{ EDXAPP_SUPPORT_SITE_LINK }}"
   ACTIVATION_EMAIL_SUPPORT_LINK: "{{ EDXAPP_ACTIVATION_EMAIL_SUPPORT_LINK }}"
+  PASSWORD_RESET_SUPPORT_LINK: "{{ EDXAPP_PASSWORD_RESET_SUPPORT_LINK }}"
   CDN_VIDEO_URLS: "{{ CDN_VIDEO_URLS }}"
   PERFORMANCE_GRAPHITE_URL: "{{ PERFORMANCE_GRAPHITE_URL }}"