Replace Fn::GetAtt Key.APIKeyId with Ref: Key

[acristin]

In some AWS regions, Fn::GetAtt Key.APIKeyId does not work, but Ref: Key also returns the API Key ID and seems to work even in these regions.

Issue #, if available

Description of changes

Description of how you validated changes

Manually deployed minimally modified test template in ap-southeast-4 both with and without this change; with change the stack deploys successfully and without, we see:

Waiter ChangeSetCreateComplete failed: Waiter encountered a terminal failure state: For expression "Status" we matched expected path: "FAILED" Status: FAILED. Reason: Template error: resource MyFirstApiKey does not support attribute type APIKeyId in Fn::GetAtt

Checklist

• Adheres to the development guidelines
• Add/update transform tests
  • Using correct values
  • Using wrong values
• Add/update integration tests

Examples?

Please reach out in the comments if you want to add an example. Examples will be
added to sam init through aws/aws-sam-cli-app-templates.

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