adds the ability to define error responses on error codes instead of default

[baywet]

fixes #165

This PR adds a new setting ErrorResponsesAsDefault default true to avoid breaking existing users.

When true, the error responses will only be described as the following

"responses": {
          "200": {
            "$ref": "#/components/responses/ODataCountResponse"
          },
          "default": {
            "$ref": "#/components/responses/error"
          }
        }

When false they'll be described as the following

"responses": {
          "200": {
            "$ref": "#/components/responses/ODataCountResponse"
          },
          "4XX": {
            "$ref": "#/components/responses/error"
          },
          "5XX": {
            "$ref": "#/components/responses/error"
          }
        }

This change is made so client generators can "better understand" what the error payloads look like and generate more accurate SDKs.

[xuzhg]

[baywet]

@xuzhg thanks for reviewing.
Holding until I get feedback on that proposal #165 (comment)

[baywet]

proposal design was approved and implemented, waiting for final review before merge.

[xuzhg]

Looks good to me, of course, if you can make the code alignment for better readability.