Simple static location sharing (#7135)

Adds maplibre as a dependency, and behind a labs flag, lets users send and receive [MSC3488](https://github.com/matrix-org/matrix-doc/blob/matthew/location/proposals/3488-location.md) style location shares - with backwards compatibility with old school `m.location` `msgtype` location shares too.

For this to work, you have to define a valid maptile server and API in your config.json's `map_style_url`.

src/settings/controllers/SettingController.ts

@@ -54,6 +54,8 @@ export default abstract class SettingController {
      */
     public onChange(level: SettingLevel, roomId: string, newValue: any) {
         // do nothing by default
+
+        // FIXME: force a fresh on the RoomView for the roomId in question
     }
 
     /**