Unify User Location / Support Location on web

[josxha]

Feature Description

It is currnetly not possible to display the user location inclusive heading on the map on web.
MapLibre GL JS offers only basic location via the GeolocateControl. The integrated location marker in MapLibre GL JS can only be enabled using that button (not programmatically) and has no support for the heading.

Because of the huge difference to MapLibre Native there are a number of potential solutions:

1. Contribute the missing functionality to MapLibre GL JS (not clear if the functionality will be accepted).
2. Write a custom location layer using JavaScript and bundle it with the package.
3. Mimic the functionality from within Dart (would replace the Location Marker on MapLibre Native as it wouldn't make sense to keep it).

Sample Use Case

• for nativation
• to locate the user

Existing Alternatives or Workarounds

The location or geolocator package can be used to fetch the users' location. It can then be displayed and updated as a custom layer on the map.

Additional Context

• Show user location independently of `GeolocateControl` maplibre/maplibre-gl-js#2960
• https://maplibre.org/maplibre-gl-js/docs/examples/locate-user/

[josxha]

I'm thinking about implementing a platform independent solution in dart using geolocator.
We would then avoid problems like maplibre/flutter-maplibre-gl#510