Auth schema validation

[tiberiu89]

What happened:
Following the specs for 0.8, I can't seem to make auth definition to work

"auth": [
    {
      "name": "azure",
      "scheme": "oauth2",
      "properties": {
        "grantType": "clientCredentials",
        "clientId": "${ $SECRETS.AZURE_CLIENT_ID }",
        "clientSecret": "${ $SECRETS.AZURE_CLIENT_SECRET }"
      }
    }
  ],

the workflow validator throws a lot of errors around this. like fields must be string, missing properties that should be defined for other scheme types etc.

What you expected to happen:
Pass validation