Issue #3219157: Support Windows file paths

[mglaman]

Would benefit from manual testing or an AppVeyor run on Windows.

NOTE Leaving as a Draft until manual review. Also, not sure if we should go down the Windows runner rabbithole – specifically with trying to configure the Composer VCS URL.

How to add this PR to your Drupal project:

cd /path/to/drupal/recommended-project
composer config repositories.1 vcs https://github.com/bluehorndigital/drupal-rector.git
composer require palantirnet/drupal-rector:dev-issue-3219157
cp vendor/palantirnet/drupal-rector/rector.php .
php vendor/bin/rector 

[bbrala]

This can be closed imo. Windows support is not something that's really relevant in my eyes