Add openapi response definitions to approle/path_role.go (#18198)

This PR modifies the path schema of `approle/path_role.go`, switching the old `Callbacks` to the equivalent `Operations` objects with a list of response fields for the 200 responses. This will allow us to generate a response structures in openapi.json. This PR is split out from #18055 along with #18192.

### Example

For `GET "/auth/approle/role/{role_name}/bind-secret-id"` path, it will update the response as follows:

```diff
        "responses": {
          "200": {
            "description": "OK",
++            "content": {
++              "application/json": {
++                "schema": {
++                  "$ref": "#/components/schemas/ApproleRoleBindSecretIdResponse"
++                }
++             }
            }
          }
        }
```

And will add the actual response structure:

```diff
++      "ApproleRoleBindSecretIdResponse": {
++        "type": "object",
++        "properties": {
++          "bind_secret_id": {
++            "type": "boolean",
++            "description": "Impose secret_id to be presented when logging in using this role. Defaults to 'true'."
++          }
++        }
++      },
```