Feature request: CID compression

[DavidSchinazi]

One of the features of the original MASQUE proposal was the ability to compress QUIC connection IDs to minimize encapsulation overhead. This might no longer be necessary now that we have "forwarded mode", but I'm filing this issue so we discuss whether CID compression is still relevant or not. This feature would be useful for use cases that cannot accept the reduced security properties of forwarded mode, but we should discuss as a WG whether such use cases exist in real life and whether we want to support them.