Introduce everything playbook, which runs all non-initial setup roles

It runs the maintenance playbook and then all other non-initial setup
roles, which aren't covered by the maintenance playbook.

inventories/hetzner/hosts.yaml

@@ -10,3 +10,6 @@ all:
     Debian_12_Hosts:
       hosts:
         cit-ansible-test:
+    Docker_Hosts:
+      hosts:
+        cit-ansible-test:

playbooks/everything.yaml

@@ -0,0 +1,7 @@
+- name: Run maintenance playbook
+  ansible.builtin.import_playbook: maintenance.yaml
+
+- name: Ensure Docker for Docker_Hosts
+  hosts: Docker_Hosts
+  roles:
+    - docker