Configure and document phpstan for ddev and GitLabCI, fix issues, disallow failures

1. 📌 Clean up phpcs issues, disallow failures Fixed is in.
2. Ddev Drupal Contrib contains a custom command ddev phpcs out of the box. Should be easy to copy over docs for this command and maybe the others as well.

We should create a follow-up to document phpstan, which doesn't have a custom command.

When I run ddev phpcs locally it generates a phpcs.xml.dist file whose contents are an HTML 404!

Should we add a phpcs.xml file?

Ah I see now this was for PHPstan.

Automatically closed - issue fixed for 2 weeks with no activity.