Support vertical exaggeration of 3D Tiles

[OmarShehata]

This was requested on the forum here (https://community.cesium.com/t/3d-tiles-exaggeration/9423/3) and here (https://community.cesium.com/t/how-to-change-the-scale-for-box-defined-tilesets/9131/3).

The idea is to vertically exaggerate 3D Tilesets in the same way you can terrain, often for the same reasons (to make it easier to see certain features).

This is a Sandcastle example @lilleyse put together showing one way to do this today just by using the 3D Tilesets model matrix/transform to scale it.

The issue with this is that it's scaling from one fixed point. Stuart Attenborrow explains the problem with this on the forum with these two gifs:

What's currently happening:

What should instead be happening:

I believe this scaling would need to happen in the shader for this to have the desired effect.

[dementiev]

+1, any updates on this?

[OmarShehata]

We aren't actively working on this at the moment but we'll add to this issue if there's any update!

[avh]

Any updates? I would love to see this feature implemented...

[bmckilligan]

Just wondering if there has been any developments on this. or perhaps even an api for point clouds that includes longitude ,latitude, elevation properties

[vectoron]

I have a need this feature to be used with the Google tile set.

[ggetz]

Support added in #11655