Map card location marker

This release adds a client-side location marker to oref-alert-map. The new show_location option is enabled by default and displays the viewing device's location when browser geolocation is available and permission is granted. The marker is client-side only and does not affect auto_fit, which continues to fit only alert and pre-alert areas. If you do not want to show the device marker, set show_location: false in the card configuration.

Full Changelog: v6.16.1...v6.17.0