Adds support for reference types on Input fields

[NeedleInAJayStack]

This adds support for recursive inputs (inputs that reference themselves). For example, the following is now a valid input definition:

input BoolExp {
  and: [BoolExp]
  or: [BoolExp]
  val: Bool
}

This builds on the Type and Interface recursion support (via TypeReference), by extending that functionality to Inputs as well.

It also renames a few Input Field types to be more consistent with the equivalent Type Field types

[paulofaria]

LGTM! Feel free to merge and tag it! 🙂

[NeedleInAJayStack]

@paulofaria Thanks for the review! I'm happy to merge and tag it, but I think I need to be given write access to this repo to do so...

[NeedleInAJayStack]

@paulofaria Hey, just a reminder that I'm happy to merge and tag, but I don't have write access. Any chance you could provide me with it?

[paulofaria]

Hey! I'll do that Today. Sorry.

[paulofaria]

@alexsteinerde Did you receive the invitation?

[paulofaria]

@alexsteinerde Sorry, the message was meant for @NeedleInAJayStack.

[paulofaria]

@NeedleInAJayStack I created a Maintainers team. You should now have access to all repos. 😄

[NeedleInAJayStack]

Awesome, I do have access now! Thanks @paulofaria

[NeedleInAJayStack]

@paulofaria I added 'macos-latest' to the CI build file so that we won't run into PR "status check" issues in the future. However, the commit reset the approval. Do you mind re-approving this?

[paulofaria]

Done!