Defines the Passable objects, and the passStyleOf function for classifying them according to their PassStyle.
See types.js for the actual type definitions. See also CopyRecord guarantees and CopyArray guarantees.
The Passable objects are those that can be passed by the @endo/marshal package. Thus Passable defines the layer of abstraction on which we need broad agreement for interoperability. One type of Passable is the Tagged object, which is the extension point for defining higher level data types, which do not need such broad agreement. The main such higher layer of abstraction is provided by the @endo/patterns package.