Can't configure extra parameters for live migration uri in libvirt

[Takashi Kajinami]

In libvirt we can add some extra parameters into migration target uri in query parameter format.[1]
 [1] https://libvirt.org/remote.html
This is still vlaid for some usecases. For example in TripleO we define a path for key file to authenticate to the remote node by keyfile parameter.

However, since live_migration_uri was deprecated and replaced by live_migration_scheme, there are no available methods to configure this without using the deprecated parameter live_migration_uri.
We need some additional option like live_migration_extraparams which can be used to define extra parameters, Otherwise it can break existing deployment which requires extra parameters configured.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/682019

[Takashi Kajinami (kajinamit)]

Seems this is a duplicate (or a subset) of https://bugs.launchpad.net/nova/+bug/1671288

[OpenStack Infra (hudson-openstack)]

Change abandoned by Takashi Kajinami (<email address hidden>) on branch: master
Review: https://review.opendev.org/682019
Reason: I'll abandon this patch as we have an existing patch proposed on gerrit[1] which seems much better than this
[1] https://review.opendev.org/#/c/456571/

Thanks Stephen for timely notice!

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/c/openstack/nova/+/915481