fix: allow sam to deploy templates contain CFN Lambda Function resources with Image package type, and its code is local image uri.

[moelasmar]

Which issue(s) does this change fix?

sam deploy fail to deploy the a template that contains Lambda function with Image Package Type, and refer to a local image uri. example template:

Resources:
  HelloWorldFunctionRole:
    Type: AWS::IAM::Role
     ......
  HelloWorldFunction:
    Type: AWS::Lambda::Function
    Properties:
      PackageType: Image
      .... 
      Code:
        ImageUri: func217e03a4:latest

This PR also fixes sam build for the same template.

Why is this change necessary?

How does it address the issue?

What side effects does this change have?

Checklist

• Add input/output type hints to new functions/methods
• Write design document (Do I need to write a design document?)
• Write unit tests
• Write/update functional tests
• Write/update integration tests
• make pr passes
• make update-reproducible-reqs if dependencies were changed
• Write documentation

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[okofish]

Is it intentional that SAM CLI is now requiring both DockerContext and Dockerfile metadata entries to be present? This change broke sam build for my template that had only DockerContext and no Dockerfile.

I'm not clear on the reasoning here but it seems like it would be better to require either property rather than both.