Fixes: 1) Correct `parameter_name` assignments in BrandAdminFilter, CategoryAdminFilter, TagsAdminFilter, and VendorAdminFilter to use plain strings;
Extra: None;
Fixes: 1) Correct parameter name value extraction to use `current` in `BaseAutocompleteFilter`;
Extra: 1) Refactor HTML rendering in `BaseAutocompleteFilter` for readability; 2) Add comments to explain purposes in the new template.