Rector setup in starter plugin is abandoned

### Description of the bug

create-wordpress-plugin includes a Rector configuration: https://github.com/alleyinteractive/create-wordpress-plugin/pull/426

After creating and configuring a new project, the `rector/rector` package is moved to the root `composer.json` file, but not the `rector` and `rector:fix` commands that were included in the plugin's old `composer.json`, nor the `rector.php` configuration file, which is left in the plugin directory.

### Steps To Reproduce

Run the configuration script for a new project.

### Additional Information

_No response_