Standalone app api v3 (#2772)

Added file io, and updated some ui elements.
Also added Digital Rain standalone app for an example.

firmware/application/apps/ble_rx_app.cpp

@@ -640,6 +640,7 @@ BLERxView::BLERxView(NavigationView& nav)
     };
 
     options_filter.on_change = [this](size_t index, int32_t v) {
+        (void)v;
         filter_index = (uint8_t)index;
         recent.clear();
         recent_entries_view.set_dirty();