CIP-0116 | Add Conway JSON schema

[klntsky]

List of changes in this PR (from #912 (comment)):

• Add Conway era schema
• Add required fields to UnitInterval
• Add required fields to plutusData variants
• Replace additionalProperties with unevaluatedProperties
  • See this issue for more details. In summary: schemas with unevaluatedProperties are easier to compose.
• Add examples for some types
  • Useful when generating values from these schemas

The corresponding tests are located at https://github.com/mlabs-haskell/cip-0116-tests

[rphair]

Reviewing in response to ping from @nazrhom in #869 (comment) - I think I had expected @Ryun1 to yea or nea this one and then I think it fell through the cracks past all of us 😬 ... tagging Last Check to ensure it doesn't evade us past the next CIP meeting (07 January), but also polling other editors for hopefully a review & merge before then.

[nazrhom]

Thanks @rphair

I can't edit the original comment, but here is a list of changes in this PR:

• Add Conway era schema
• Add required fields to UnitInterval
• Add required fields to plutusData variants
• Replace additionalProperties with unevaluatedProperties
  • See this issue for more details. In summary: schemas with unevaluatedProperties are easier to compose.
• Add examples for some types
  • Useful when generating values from these schemas