Lambda shareable events

### Name of the resource

AWS::Lambda::Function

### Resource name

_No response_

### Description

Add support for Lambda [Shareable test events](https://docs.aws.amazon.com/lambda/latest/dg/testing-functions.html#creating-shareable-events)

### Other Details

Alternative solution would be to add support for this via CDK: https://github.com/aws/aws-cdk/issues/19471

Start with the AWS::Lambda::Function resource and the linked AWS Lambda documentation on shareable test events. Review the alternative CDK issue to understand the proposed scope; done means CloudFormation supports creating and using Lambda shareable test events. No repository files or tests are named.

Written by the indexing model from the issue text.