conf: domain: Insert auto-added controllers in same order as in XML parser

conf: domain: Insert auto-added controllers in same order as in XML parser

'virDomainDefAddController' which is used in code-paths which auto-add
controllers to the definition such as 'virDomainDefMaybeAddController',
'virDomainDefAddUSBController', 'qemuDomainDefAddDefaultDevices' was
adding the controller at the end of the list. However that is not how
the XML parser would order the controller in the list as it uses
virDomainControllerInsert grouping them by type and additional
properties.

This would cause that auto-added controllers would re-order:
 - between first and any subsequent run of the VM (even on commandline)
 - after a libvirtd/virtqemud restart
 - after any update of the definition based on the 'define' operation
   (e.g. virsh edit)

To ensure that the ordering of controllers is identical always use
virDomainControllerInsert.

Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>