Sometimes we need to determine the class of a javascript object. Currently, class membership testing can be done by prototype object comparison, but there is nothing preventing a user from overriding the __proto__ field of an object.

It would be helpful to determine the C++ className of an object in a way that cannot be overridden by a user.

We propose adding a new `mongoTypeName()` function that would return the className for an object created from a MongoDB class (e.g. NumberInt, OID, etc).