feature to drain the next value from the buffer

[scott-wyatt]

TLDR: See #34

Summary:
Occasionally in application development, a certain condition will arise where the next value being produced by a parser needs to be drained from the buffer as a string into memory.

A Drain next value as a string function should be able to take any JSON value and drain all the upcoming events so they are not dispatched and collect the buffer as a string until the value's terminus.

Purpose:
A JSON value is seldom the last form a given piece of data will be in. Event streams are made to dispatch to other consumers, and this function would make it possible to dispatch the next value as a completed string to another consumer.

Use Cases:

1. Passing a value to another parser

[Tpt]

Yes! I see multiple slightly different use cases from it:

• drain next value and discard it (aka ignore a part of this JSON)
• drain next value and return it as a string (aka extra a JSON fragment)
• drain next value and serialize it to this given structure implementing serde::Deserialize (deserialization of smaller chunks)

[scott-wyatt]

@Tpt, exactly! I have this currently in #34 for sync. I've run 2-3 TB of random json through it and it seems to be working okay. Not optimized, but just wanted to draft what a feature like this would be like.