Deployments needs to support AAD

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Deployment will work currently only with key based auth to the AOAI resource.

To implement AAD we need the following:

Solution 1: UAI

During the azd provision, we provision a user-assigned-identity. When end endpoint is created, this UAI is added to it. The UAI gets added the Cognitive Services OpenAI Contributor/User role towards the AOAI resource.

Solution 2: SystemAssigned

During the azd provision, we get the system identity of the endpoint, and we RBAC it to get the right role towards the AOAI resource.