Add a new UpnpRegisterRootDevice4 which allow user to specify a
description URL to be returned for legacy CPs (for example, CPs
searching for a v1 when the device is v2). Most of those CPs does not
work if they found a v2 in the XML description, so this new function is
only used to solve interoperability issues.
(cherry picked from commit 11f9a2bafe15f7ebb38342f26fb91258390a64ef)
daec6a0321