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`.

package.json

@@ -57,6 +57,7 @@
     "@babel/runtime": "^7.12.5",
     "@sentry/browser": "^6.11.0",
     "@sentry/tracing": "^6.11.0",
+    "@types/geojson": "^7946.0.8",
     "await-lock": "^2.1.0",
     "blurhash": "^1.1.3",
     "browser-encrypt-attachment": "^0.3.0",
@@ -83,6 +84,7 @@
     "katex": "^0.12.0",
     "linkifyjs": "^2.1.9",
     "lodash": "^4.17.20",
+    "maplibre-gl": "^1.15.2",
     "matrix-js-sdk": "github:matrix-org/matrix-js-sdk#develop",
     "matrix-widget-api": "^0.1.0-beta.18",
     "minimist": "^1.2.5",