Bring your own container registry

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**Description**
Add support to create Lambda functions from container images hosted in third-party container registries.

**Additional Context**

1. What authentication methods should we support?
2. What container registries do you use?
3. How would you expect Lambda to connect to your network?

Start with the issue description and its authentication, registry, and network-connectivity questions. Determine which third-party registries and authentication methods should be supported, then define completion as Lambda functions being creatable from images hosted in those registries.

Written by the indexing model from the issue text.