Plugin groups (#30320)

* add new pluginapi methods

* SAML login hook

* set ReAddRemovedMembers to true for plugin groups

* change to DoLogin signature for SAML

server/i18n/en.json

@@ -5314,6 +5314,10 @@
     "id": "app.group.id.app_error",
     "translation": "invalid id property for group."
   },
+  {
+    "id": "app.group.license_error",
+    "translation": "LDAP license required."
+  },
   {
     "id": "app.group.no_rows",
     "translation": "no matching group found"