ref(inventory): Create target type indirection

Allows setting the current target to any of the groups sorted by target
type (i.e. 'what' type of machine it is). For example, we currently
target our system to a 'workstation' type machine. But we could switch
it to a headless machine which would not install any of the DE/GUI
grouped packages.

inventory.yaml

@@ -1,3 +1,17 @@
+# 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:
+
+target_system:
+  children:
+    chroot_target:
+  vars:
+    desired_package_state: latest
+
 hostsystem:
   hosts:
     127.0.0.1:
@@ -15,15 +29,9 @@ local_target:
     void_local:
       ansible_host: 127.0.0.1
 
-target_system:
-  children:
-    chroot_target:
-  vars:
-    desired_package_state: latest
-
 interface:
   children:
-    target_system:
+    workstation:
   vars:
     fonts:
       - nerd-fonts-otf
@@ -47,7 +55,8 @@ interface:
 
 terminal:
   children:
-    target_system:
+    workstation:
+    headless:
   vars:
     packages_terminal:
       - abduco