Allow users to select an image source when creating a containerized function app

[motm32]

Here is the proposed flow

1. Options – Quickstart/Container Registry/Build an image from local workspace project with Dockerfile.
2. Note: To support both public/private registries
3. Select a container registry – Docker Hub/ACR/other public registry
4. If ACR -> Select an ACR registry
5. Select a repository
6. Select a tag