port stretchable icons from -js

[ansis]

I'm opening this issue so that render test ignores can point to something.

prs:
mapbox/mapbox-gl-js#8997
mapbox/mapbox-gl-js#9041
mapbox/mapbox-gl-js#9045

[LukasPaczos]

/cc @mapbox/navigation-android @mapbox/navigation-ios @andrewychen

A very cool new feature that could enhance route/destination callouts.

[1ec5]

This feature has landed in iOS map SDK v5.8.0. It only works via runtime styling because the server-side changes haven’t landed yet.