Update Imported Model Vertices

[Marcello_Fabbiani]

This PG is working nice, you can update vertex data by clicking the sphere https://playground.babylonjs.com/#VE6GP#559

Now, i want to update an imported mesh, which seems to be unupdatable by default https://playground.babylonjs.com/#VE6GP#558

[musk]

Fail to update vertex buffer of an Imported GLTF file

You should use setVerticesData instead of updateVerticesData, which only works if the buffer has been created as updatable in the first place.