AWS::CodeBuild::ProjectPolicy

1. Title -> AWS::CodeBuild::ProjectPolicy
2. Scope of request -> AWS::CodeBuild::ProjectPolicy - can create resource via API, but not via CloudFormation
3. Expected behavior -> In Create, it should call [CodeBuild.PutResourcePolicy](https://docs.aws.amazon.com/codebuild/latest/APIReference/API_PutResourcePolicy.html) on a referenced project
5. Links to existing API doc ->
* [CodeBuild.PutResourcePolicy](https://docs.aws.amazon.com/codebuild/latest/APIReference/API_PutResourcePolicy.html)
* [Sharing a project CodeBuild User Guide Documentation](https://docs.aws.amazon.com/codebuild/latest/userguide/project-sharing.html#project-sharing-share)
6. Category tag -> Developer Tools
7. This will help us create CodeBuild jobs in different AWS accounts, but orchestrate and call them using IAM principals from other accounts.

Start with the linked CodeBuild.PutResourcePolicy API reference and the project-sharing user guide to understand the requested CloudFormation coverage. Done means AWS::CodeBuild::ProjectPolicy can be created through CloudFormation and invokes PutResourcePolicy for a referenced project, including the cross-account use case described.

Written by the indexing model from the issue text.