Adds a binding of external key to internal id to
map. The binding will be done with keySize bytes of what key points to, where keySize is the parameter that was used in the mapCreate call. The return value uniquely identifies this binding; it can later be given as an argument to
mapRemoveBinding. A return value of ERR_BIND indicates that the key is already bound in the map to a different id. If the key is already bound to the same id, that binding is returned.
Binding mapBind(Map map, void *key, void *id)