feat: add cobbler profile

- add datavol to cobbler nodes
- add cobbler profile
- add cobbler role hieradata
- manage selinux where required for cobbler
- manage service cname

site/profiles/templates/cobbler/main.ipxe.erb

@@ -0,0 +1,47 @@
+#!ipxe
+dhcp
+
+# Some menu defaults
+set menu-timeout 5000
+set submenu-timeout ${menu-timeout}
+set menu-default cobbler
+
+:start
+menu iPXE boot menu
+item --gap --                   ----------------------------- Cobbler ------------------------------------
+item            cobbler                 Cobbler (kickstart or boot from disk)
+item --gap --                   ------------------------- Advanced options -------------------------------
+item --key s    shell                   Drop to iPXE shell
+item --key r    reboot                  Reboot
+item
+item --key x    exit                    Exit iPXE and continue BIOS boot
+choose --timeout ${menu-timeout} --default ${menu-default} selected || goto cancel
+set menu-timeout 0
+goto ${selected}
+
+:cancel
+echo You cancelled the menu, dropping you to a shell
+
+:no_system
+echo No system configuration found for MAC address ${mac}
+goto exit
+
+:shell
+echo Type 'exit' to get the back to the menu
+shell
+set menu-timeout 0
+set submenu-timeout 0
+goto start
+
+:reboot
+reboot
+
+:exit
+exit
+
+###
+### Custom menu entries
+###
+
+:cobbler
+chain --autofree http://${next-server}/cblr/svc/op/gpxe/mac/${net0/mac} || goto no_system