Support AWS::Lambda::Alias type resolving

[rangerthegood]

Which issue(s) does this change fix?

#7832

Why is this change necessary?

Without this change it is not possible to use start-api when your SpecRestApi is wired up with a Lambda function Alias versus just a Lambda, which would work fine.

How does it address the issue?

The code change introduces a new type resolvers for AWS::Lambda:Alias, This resolver works by looking at the FunctionName property. Once it has access to the function name it uses the existing arn_resolver function to retrieve the result.

What side effects does this change have?

None, that I'm aware of, I've introduced an additional test case to demonstrate the feature, and the existing test cases all still pass.

Mandatory Checklist

PRs will only be reviewed after checklist is complete

• Add input/output type hints to new functions/methods
• Write design document if needed (Do I need to write a design document?)
• Write/update unit tests
• Write/update integration tests
• Write/update functional tests if needed
• 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.