add map

[r10s]

this pr adds a map that showing locations to iOS.

while android and desktop use mapbox, we're using leaflet here, encapsulated in a mostly normal webxdc.

• mapbox was a a source of all kind of issues in the last (telemetry hard to disable, being flagged as "bad" on fdroid and things like that)
• the webxdc is only 50k in side (android mapbox is about 4mb)
• leaflet is much faster when it comes to many poi
• idea is that the webxdc can be replaced by the end-user later (eg. by sending a own variation to saved-messages)
• finally, we should consider to switch to leaflet (or map-webxdc in general) also on other platforms (there is a small wrapper that converts core-location-api to webxdc-updates - currently, that part is in swift, but could also go to core-rust)
• we can then much easier add more functionality and controls to the webxdc - and also things like tor become easier as we have to consider one routing less (the map is a webxdc and webxdc has to be considered anyways)

some impressions:

(the third image is a result from location-streaming-api some years ago, however, how we have nice test-data by that :)

main open point is that the xdc is currently visible in the saved-messages chat, we should consider if it is better to hide it somehow.

apart from that, things work :)