[New feature] Content Moderator - Image screening

[nrobert]

Implementation of Content Moderator image version:

• Documentation: https://docs.microsoft.com/en-us/azure/cognitive-services/content-moderator/image-moderation-api
• API: https://westus.dev.cognitive.microsoft.com/docs/services/57cf753a3f9b070c105bd2c1/operations/57cf753a3f9b070868a1f66c