JetSmartFilters For Elementor 3.6.6

* UPD: front-end code refactoring;
* ADD: allow to choose additional provider for filters;
* ADD: show empty terms for checkboxes, select, radio and visual filters;

* ADD: compatibility the Indexer with WPML plugin;
* FIX: applying Indexer functionality for page reload filters;
* FIX: compatibility the Indexer with JetPopup plugin;
* FIX: Checkbox, Check Range, Radio filters horizontal layout style controls;
* FIX: hierarchy levels options list on redirect;
* FIX: various minor fixes.

* ADD: Allow to get options for select, radio and checkboxes from custom field data (for JetEngine or ACF);
* FIX: Various fixes.