inventory: Add create_groups option

This adds the create_groups option to the inventory, which allows to
control the creation of groups from labels on VirtualMachines. By
default it is disabled.

Signed-off-by: Felix Matouschek <fmatouschek@redhat.com>

tests/integration/targets/inventory_kubevirt/test.kubevirt.yml

@@ -2,3 +2,4 @@ plugin: kubevirt.core.kubevirt
 connections:
   - namespaces:
       - default
+    create_groups: yes

tests/integration/targets/inventory_kubevirt/test.label.kubevirt.yml

@@ -2,4 +2,5 @@ plugin: kubevirt.core.kubevirt
 connections:
   - namespaces:
       - default
+    create_groups: yes
     label_selector: app=test

tests/integration/targets/inventory_kubevirt/test.net.kubevirt.yml

@@ -2,4 +2,5 @@ plugin: kubevirt.core.kubevirt
 connections:
   - namespaces:
       - default
+    create_groups: yes
     network_name: bridge-network