🛠 Tooling: Investigate reusable workflows in GitHub Actions

### Bug Report Checklist

- [X] I have tried restarting my IDE and the issue persists.
- [X] I have pulled the latest `main` branch of the repository.
- [X] I have [searched for related issues](https://github.com/JoshuaKGoldberg/create-typescript-app/issues?q=is%3Aissue) and found none that matched my issue.

### Overview

Right now, this template uses a [Composite Action](https://docs.github.com/en/actions/creating-actions/creating-a-composite-action) to reuse the steps shared between most actions: https://github.com/JoshuaKGoldberg/create-typescript-app/blob/259e81a1dbb6493683b2d417ae36adb54d36fec7/.github/actions/prepare/action.yml.

But what about a [Reusable Workflow](https://docs.github.com/en/actions/using-workflows/reusing-workflows)? Would that be better/worse/different in some way? I haven't investigated, but would love to know. Investigation required.

### Additional Info

Suggested by @JamieMagee in https://twitter.com/Jamie_Magee/status/1737535870373437447 - thanks!