Changeset 14706 for main/waeup-ansible

Add ansible role for installing letsencrypt (LE)

The letsencrypt.yml playbook is there to trigger the
letsencrypt role. It sets some important vars.

Putting all this into an own role might be overkill,
but it is good to have at least something
letsencrypt-related in the repo.

All this might be better placed in a single playbook.