Mount /lib/modules inside containers during tests

The modprobe module now checks for builtins, which aren't available inside LXC containers.
see: ansible/ansible#37150

Author: lae

tests/install.yml

@@ -17,6 +17,11 @@
       - profile: debian-stretch
         prefix: proxmox-5-
     test_hosts_per_profile: 3
+    container_config:
+      - "lxc.apparmor.profile = unconfined"
+      - "lxc.mount.auto = proc:rw sys:rw cgroup-full:rw"
+      - "lxc.cgroup.devices.allow = a *:* rmw"
+      - "lxc.mount.entry = /lib/modules/{{ ansible_kernel }} lib/modules/{{ ansible_kernel }} none bind,create=dir,ro 0 0"
 
 # Run the following within the containers in the inventory
 - hosts: all