Adding SetFileSearchableContent plugin API endpoint (#24355)

* Adding SetFileSearchableContent plugin API endpoint

* Fixing CI problems

* Fixing CI problems

* Fixing CI problems

* Fixing CI problems

* Fixing CI problems

* Exposing it to the public API

* Fix CI problems

* Adding SetSearchableContent to the pluginapi File struct

server/i18n/en.json

@@ -5247,6 +5247,10 @@
     "id": "app.file_info.save.app_error",
     "translation": "Unable to save the file info."
   },
+  {
+    "id": "app.file_info.set_searchable_content.app_error",
+    "translation": "Unable to set the searchable content of the file."
+  },
   {
     "id": "app.group.crud_permission",
     "translation": "Unable to perform operation for that source type."