Detect and list sites in a multi-site Drupal installation

[jigarius]

Tasks

• [x] Add commands to show a list of sites present in the multi-site installation
  • [x] Detect sites using sites/*/settings.php
  • [x] Detect sites using drush alias definitions
  • [x] Preferably, the list of sites should be iterable in shell scripts
• [x] Use a SiteDetector service to make the code re-usable.

Notes

• Only support D8+.
• Use PHP 8 or higher.

[jigarius]

Though this works now, I'd like to move some of the logic into a separate service, say, SiteDetector service to make the code reusable.