Add role map support for proxy auth (#19758)

* update config

* add role map support

* docs

docs/docs/configuration/reference.md

@@ -88,7 +88,13 @@ proxy:
   #       See the docs for more info.
   header_map:
     user: x-forwarded-user
-    role: x-forwarded-role
+    role: x-forwarded-groups
+    role_map:
+      admin:
+        - sysadmins
+        - access-level-security
+      viewer:
+        - camera-viewer
   # Optional: Url for logging out a user. This sets the location of the logout url in
   # the UI.
   logout_url: /api/logout