allow defining the home directory

The idea here is that we can have a backup server that should run on a
slow huge disk, and that the rest should run on your very fast nvme's.
To differentiate, you can specify where the homedir should be

roles/ppm/tasks/oneapp.yml

@@ -2,6 +2,7 @@
   ansible.builtin.user:
     name: "{{ ppm_app.user }}"
     shell: /bin/bash
+    home: "{{ ppm_app.homedir | default(omit) }}"
   register: ppm_app_user
 
 # Enabling linger will make systemd start the user-systemd for this user at bootup time