Releasy: Develop and test against Apache-Trusted-Releases

### Is your feature request related to a problem? Please describe.

This issue needs to be fleshed out with the actual tasks, so the following bullet point list is rather a draft.

* Leverage ATR OpenAPI to manage releases
* Interact with ATR/REST from our release workflows
* Define email templates for ATR

Links:
* https://release-test.apache.org/tutorial
* https://github.com/apache/tooling-trusted-release
* OpenAPI https://release-test.apache.org/api/docs

### Describe the solution you'd like

_No response_

### Describe alternatives you've considered

_No response_

### Additional context

_No response_

Start with the ATR tutorial, the tooling-trusted-release repository, and the linked OpenAPI documentation. Break the draft into concrete work for release workflows, ATR REST interactions, and email templates, with completion defined for each task before implementation begins.

Written by the indexing model from the issue text.