Stream API

[brettz9]

Per our discussion in dfahlander/typeson-registry#2 (I'm planning to reply there shortly, btw), the idea of stream support was added and for the API, the methods are to be postfixed with *Stream".

I think consideration ought to be given for supporting the definition by the type of additional encapsulators/revivers . A type might need different implementations to return synchronously or as a stream (or promise), e.g., a file's contents.

In some cases, however, like converting a stream to a Promise, we might be able to do it for them. Thus
if a type defined a stream API, a user could nevertheless allow us to convert it to a Promise on their behalf when the stream finished.

Besides cases where multiple implementations might be necessary or desirable, offering alternative APIs might be desirable for polymorphism, e.g., if a stream is normally expected in one context but one particular type were only defined to simply return a string after revival, upon using the *Stream method, the synchronously obtained result could be turned into a stream by Typeson code on the user's behalf as could be done with Promises.