Tag Folders: tag filters indicator and show settings

- Add an indicator if any tag filters are applied, so you can see if there are any filters even if the list is collapsed
- Save collapse state of the tag list
- Fix folders vanishing if tag filters are applied (now really)

public/scripts/power-user.js

@@ -234,6 +234,7 @@ let power_user = {
     encode_tags: false,
     servers: [],
     bogus_folders: false,
+    show_tag_filters: false,
     aux_field: 'character_version',
     restore_user_input: true,
     reduced_motion: false,