ref(inventory): Split up inventory into group vars

One inventory targets a local machine (`inv-local.yaml`, chosen by default)
while the other targets a chrooted installation accessible from another
system, usually in the `/mnt/void` directory (`inv-chroot.yaml`, has to
be called like `ansible-playbook -i inv-chroot.yaml`).

inv-local.yaml

@@ -0,0 +1,23 @@
+---
+target_system:
+  children:
+    local_target:
+      hosts:
+        void_local:
+          ansible_host: 127.0.0.1
+          ansible_connection: ansible.builtin.local
+
+hostsystem:
+
+# example separation of packages: GUIs and DEs in workstation, only terminal in headless
+workstation:
+  children:
+    target_system: # mark this the current target system
+
+headless:
+  children:
+    workstation:
+
+desktop:
+  children:
+    workstation: