Location sharing: don't hardcode API key

In an effort to make it easier for forks to (a) use their own
API keys (b) change map styles or maybe even providers, move
the MapTiler key out of the source code and pass it in via
env var or property.

Also refactor the utility classes slightly to keep all the URL
related functions together, to reduce the chance of collisions
when maintaining such forks.

features/location/impl/src/main/kotlin/io/element/android/features/location/impl/map/MapView.kt

@@ -50,7 +50,7 @@ import com.mapbox.mapboxsdk.plugins.annotation.SymbolManager
 import com.mapbox.mapboxsdk.plugins.annotation.SymbolOptions
 import com.mapbox.mapboxsdk.style.layers.Property.ICON_ANCHOR_BOTTOM
 import io.element.android.features.location.api.Location
-import io.element.android.features.location.api.internal.buildTileServerUrl
+import io.element.android.features.location.api.internal.tileStyleUrl
 import io.element.android.libraries.designsystem.preview.ElementPreviewDark
 import io.element.android.libraries.designsystem.preview.ElementPreviewLight
 import io.element.android.libraries.designsystem.theme.components.Text
@@ -102,7 +102,7 @@ fun MapView(
                 isCompassEnabled = false
                 isRotateGesturesEnabled = false
             }
-            map.setStyle(buildTileServerUrl(darkMode = darkMode)) { style ->
+            map.setStyle(tileStyleUrl(context, darkMode)) { style ->
                 mapRefs = MapRefs(
                     map = map,
                     symbolManager = SymbolManager(mapView, map, style).apply {