Add LatLng Location Input Plugin

Problem/Motivation

https://www.drupal.org/project/leaflet/issues/3254562 add functionality to sync Leaflet map center LatLng into an individual Latitude and Longitude textfield pair. It is working well with geofield proximity filter (with split Latitude and Longitude textfield pair) but nto for search_api_location:

• RAW location input combine Latitude and Longitude into SINGLE textfield
• MAP location input have individual Latitude and Longitude textfield but hidden; moreover its min-map functionality is useless if combine with Leaflet SyncView

Here I combine both logic from RAW and MAP, but just keep the Latitude and Longitude textfield in pair: