Allow MapView.lookAt() to obey a target's altitude, so that the camera will also move up/down.

[trusktr]

Is your feature request related to a problem? Please describe.

When calling mapView.lookAt({target}), altitude is ignored, so if an object moves upward (f.e. an helicopter taking off) then the object will go out of view because the camera altitude stays the same.

Describe the solution you'd like

We should have an option to specify that it should also follow the given target's altitude.

Describe alternatives you've considered

When we make custom cameras easier to use in #1, an alternative would be to tell the MapView to use a camera that is a child of a moving object and it would simply work.

Additional context

This would be useful when animating a object (f.e. in an animation frame loop) and wanting the camera to lookAt the object each frame as the object moves upwards into the sky.