Allow workflow specs to be created in code with the assistance of a CLI that creates helpers for building them.

[nolag]

Note: No need to review the generated code in the same package as it's using an existing generator and just replacing a comment.

To come in later PRs for the builder:

Multiple functions in a capability (eg: ocr will have DataFeeds and custom, chain reader will have a bunch of methods).

For now, they will just have different json schemas with something like "type" defined as a fixed string for each of them.

Custom compute (in builder, making it testable and plugging into the engine will be it's own PRs also to keep things smaller)