Add rule to check `format` is allowed for `type`

OpenAPI v2 has a number of well-defined type/format combinations.

https://github.com/OAI/OpenAPI-Specification/blob/main/versions/2.0.md#data-types

and autorest recognizes several more. 

https://github.com/Azure/autorest/blob/main/packages/libs/openapi/src/formats.ts

Anything outside of this should be flagged for discussion. 