feat: support openapi yaml include validation

[NickHeap2]

Which issue(s) does this change fix?

#3041

Why is this change necessary?

If you are using OpenAPI yaml specifications it makes sense to use them for the API DefinitionBody like this:

      DefinitionBody:
        'Fn::Transform':
          Name: AWS::Include
          Parameters:
            Location: openapi.yaml

Whilst this is valid in a template it is currently not supported by sam validate.

How does it address the issue?

This change detects this pattern and replaces the DefinitionBody with the actual contents of the file allowing the validation to succeed.

What side effects does this change have?

Potentially someone could be relying on the existing behaviour where it fails for this pattern to prevent that pattern being used.

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.

[jfuss]

Thank you for the contribution!

Just a couple small comments. If you could address those, that would be awesome.

[NickHeap2]

@jfuss any chance of getting this across the line?

[jfuss]

@NickHeap2 Apologizes on the slow response here. I was on parental leave.

I am getting back and collecting the PRs I need to respond too and looking to scope time in the coming weeks to tackle them in batches.

[jfuss]

LGTM. Thanks for the contribution @NickHeap2

I will find another member of the team to review as well (as we required two approvals).

[mingkun2020]

Hi @NickHeap2, we have to revert the changes due to the bug reported in this issue#3676 by PR#3685. The validation failed when the location is an intrinsic function like Location: !Join ["", ["s3://", !Ref SomePath, "/openapi.yaml"]].

[NickHeap2]

OK @mingkun2020 I'll get the change reworked as soon as I get a chance.