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/templates/upstream.json.j2

@@ -0,0 +1,38 @@
+{
+    "@id": "{{ stack_name }}_upstream",
+{% if server_domain is not undefined and not none %}   
+    "match": [
+        {
+            "host": [
+{% if subdomain_alias is not undefined and not none %}
+                "{{ subdomain_alias }}.{{ server_domain }}"
+{% else %}
+                "{{ stack_name }}.{{ server_domain }}"
+{% endif %}
+            ]
+        }
+    ],
+{% else %}
+    "match": [
+        {
+            "path": [
+{% if subdomain_alias is not undefined and not none %}
+                "/{{ subdomain_alias }}*"
+{% else %}
+                "/{{ stack_name }}*"
+{% endif %}
+            ]
+        }
+    ],
+{% endif %}
+    "handle": [
+        {
+            "handler": "reverse_proxy",
+            "upstreams": [
+                {
+                    "dial": "{{ stack_name }}_web:80"
+                }
+            ]
+        }
+    ]
+}