v0.0.1 Core API for v3

## Background

Currently many custom nodes break during ComfyUI updates because they are using functions where the implementation or definition changes. This occurs in both the frontend and backend. Our goal is to provide a Python and JS API that is backwards compatible and stable for node developers to use.

[More info](https://blog.comfy.org/i/165338805/curated-api-for-backward-compatibility)

## In Scope

- Ship v0.0.1 of the Open-Source backend API with backward-compatibility support
- Will include very few initial APIs. Support things that are annoying now and probably won’t change from V3 Schema
- `SetProgressState`
- `GetProgressState`
- `writeFileToDisk`
- `writeBatchImageToDisk`
- SamplingFunctions?