add Style Model
Adds a model to be used in the style. This API can also be used for updating a model. If the model for a given `modelId` was already added, it gets replaced by the new model. The model can be used in `model-id` property in model layer.
Return
A string describing an error if the operation was not successful, empty otherwise.
Parameters
model Id
An identifier of the model.
model Uri
A URI for the model.