Export SuperJSONResult type

[tmcw]

We were previously using SuperJSON v1, and importing from dist/types to get the SuperJSONResult type. Now that it's at v2 and there's an explicit exports entry in superjson, we can't do that, and it'd be nicer if index.ts re-exported SuperJSONResult to make that access possible.

This is for things like making sure that a zod parser that tests whether a value is "like" a SuperJSONResult is accurate, or just for typing the output of functions that return SuperJSON-serialized data.

[Skn0tt]

That's a good idea! Do you wanna open another PR for this?

[tmcw]

Sure! PR: #272