bug: inconsistent types for OAS3_1 schemas

[jeremyfiel]

https://github.com/Redocly/redocly-cli/blob/f11ebcbe1349c5593fbd40ca14259ff432a04b5a/packages/core/src/typings/openapi.ts#L160-L164

https://github.com/Redocly/redocly-cli/blob/f11ebcbe1349c5593fbd40ca14259ff432a04b5a/packages/core/src/types/oas3_1.ts#L90-L185

Should these two separate typings be refactored to use only one of them across the core package? The openapi.ts typing does not include the unevaluated* keywords required for OAS 3.1.x /JSON Schema 2020-12 schemas.

I think this relates to https://github.com/Redocly/redocly-cli/issues/1546 where an unexpected keyword is throwing an error, but it is indeed valid for JSON Schema 2020-12 schemas to define any arbitrary properties.

In the previous version of OpenAPI 3.0.x, the schema object was strictly defined as a superset and subset of a JSON Schema draft-04 schema, and thus not all JSON Schema related behaviors applied. The interface design of OAS3_1Schema does not allow arbitrary properties.