Stop using Ansible's cron module

This is mainly to address SSL renewal not working for us due to:
- https://github.com/ansible/ansible/issues/71213
- https://github.com/ansible/ansible/pull/71207

Using the cron module was hacky anyway. We shouldn't need an extra
level of buggy abstraction to manage a cronjob file.

roles/matrix-nginx-proxy/templates/cron.d/matrix-ssl-lets-encrypt.j2

@@ -0,0 +1,5 @@
+MAILTO="{{ matrix_ssl_lets_encrypt_support_email }}"
+15 4 * * * root {{ matrix_local_bin_path }}/matrix-ssl-lets-encrypt-certificates-renew
+{% if matrix_nginx_proxy_enabled %}
+20 5 * * * root {{ matrix_host_command_systemctl }} reload matrix-nginx-proxy.service
+{% endif %}