qemu: hotplug: Refactor/simplify PR managed addition to VM
qemu: hotplug: Refactor/simplify PR managed addition to VM

Similarly to qemuDomainDiskRemoveManagedPR make it enter monitor on
its own so that it can be reused. Future users will be in the snapshot
code and in removable media change code.

Signed-off-by: Peter Krempa <2cf5c04c61aa466e4a47bfedc747d17279c72ffc@redhat.com>
Reviewed-by: Ján Tomko <4cab11cfb98d3c937327354a78eb07dbb6ee2bc6@redhat.com>

fabianfreyer/libvirt,andreabolognani/libvirt,olafhering/libvirt,libvirt/libvirt,nertpinx/libvirt,crobinso/libvirt,fabianfreyer/libvirt,jardasgit/libvirt,jfehlig/libvirt,eskultety/libvirt,fabianfreyer/libvirt,andreabolognani/libvirt,zippy2/libvirt,crobinso/libvirt,olafhering/libvirt,zippy2/libvirt,jfehlig/libvirt,andreabolognani/libvirt,nertpinx/libvirt,eskultety/libvirt,zippy2/libvirt,eskultety/libvirt,crobinso/libvirt,nertpinx/libvirt,eskultety/libvirt,jfehlig/libvirt,nertpinx/libvirt,eskultety/libvirt,fabianfreyer/libvirt,jardasgit/libvirt,libvirt/libvirt,jardasgit/libvirt,zippy2/libvirt,fabianfreyer/libvirt,crobinso/libvirt,nertpinx/libvirt,olafhering/libvirt,jfehlig/libvirt,olafhering/libvirt,andreabolognani/libvirt,andreabolognani/libvirt,jardasgit/libvirt,jardasgit/libvirt,libvirt/libvirt,libvirt/libvirt