[xapi]: tell xenopsd to manage dom0
[xapi]: tell xenopsd to manage dom0

This is only needed because some testcases expect to be able to
call raw VBD.plug, which is a behaviour we need to stamp out.

Signed-off-by: David Scott <63c9eb0ea83039690fefa11afe17873ba8278a56@eu.citrix.com>

koushikcgit/xcp-rrdd,simonjbeaumont/xcp-rrdd,koushikcgit/xcp-networkd,djs55/xcp-networkd,sharady/xcp-networkd,djs55/xcp-rrdd,djs55/xcp-rrdd,koushikcgit/xcp-rrdd,djs55/xcp-networkd,simonjbeaumont/xcp-rrdd,koushikcgit/xcp-rrdd,johnelse/xcp-rrdd,robhoes/squeezed,johnelse/xcp-rrdd,sharady/xcp-networkd,koushikcgit/xcp-networkd,djs55/squeezed