Add support for `unevaluatedProperties` keyword

[nahcikuy]

Draft 2019-09 introduces the new keyword unevaluatedProperties, which seems not supported in this project yet.

A schema with "unevaluatedProperties": false will lead to the generated type definition containing an extra [k: string]: unknown; field, which is expected not to be seen.

Reproduction

Schema

{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "type": "object",
  "title": "Foo",
  "properties": {
    "bar": {
      "type": "string"
    }
  },
  "unevaluatedProperties": false
}

yields

export interface Foo {
  bar?: string;
  [k: string]: unknown;
}

which is expected to be

export interface Foo {
  bar?: string;
}

instead.

[OnkelTem]

@bcherny Boris, what do you think about this?

[le-u-f]

Yes that would be super cool, thanks 🎉

[decadef20]

Is there anyone working on this? I'd love to have a try.