OAS: Able to infer binary content encoding form media-type when shema is missing or empty

[ostridm]

In OpenAPI 3.0, a file upload is described using type set to string and format set to binary or base64 depending on how the file contents will be encoded. However, in OpenAPI 3.1 it is not needed to use the Schema Object for a binary file in a POST request. See considerations and example

Binary File Upload in OpenAPI 3.0

requestBody:
  content:
    application/octet-stream:
      schema:
        type: string
        format: binary

Binary File Upload in OpenAPI 3.1

requestBody:
  content:
    application/octet-stream: {}