[pve-devel] [PoC] remote migration via websocket tunneling

[Fabian Grünbichler]

this is a rough proof of concept for
- remote cluster/node configuration
- generic tunneling via websocket support in our regular API server
- basic (live) migration to a remote node/cluster

there are plenty of not-yet-implemented parts and rough edges, but I'd
appreciate input on whether we want to flesh out this approach, or try
something completely different.

storage_migrate could be ported to support a websocket tunnel as
transport as well, which would be the first basic block for
- unused disk support
- offline migration
- container migration
- replication to remote clusters/nodes

the first two could also be done by always migrating all disks via
NBD/drive-mirror.