Add basic nextcloud deployment

Uses php-fpm image and is served through a simple caddy server.
Automatically deploys by default and can be automatically deployed with
smtp e-mail sending and s3 primary object storage optionally if desired.

Utilizes some necessary hackery for container ordering and startup so
startup is relatively slow (takes around 2-5 minutes at least) but once
running should be stable and uninterrupted.

Implements health-checks for all involved containers.

Switch apache for php-fpm image

roles/nextcloud/vars/main.yml

@@ -0,0 +1,7 @@
+---
+
+stack_name: nextcloud
+
+stack_image: "nextcloud"
+
+stack_compose: "{{ lookup('template', 'docker-stack.yml.j2') | from_yaml }}"