Introduce dynamic site folder

[elvism-lullabot]

The sites/default is known as the default site directory. It'd be good to have an env variable to change that directory.

playwright-drupal/tasks/playwright.yml

Lines 65 to 66 in 6ebb053

	cp -a web/sites/default/*.php web/sites/simpletest/{{ shellQuote .test_id }}/
	cp -a web/sites/default/*.yml web/sites/simpletest/{{ shellQuote .test_id }}/