rpc_transport

The connection a request came on. Also the rpc_transport telemetry attribute, on the rpc span.

Value	Meaning
`socket`	The per-user socket.
`libp2p`	A host peer stream (`/lvcs/rpc/1`).
`ice`	The RPC data channel of a WebRTC connection signaled through the tracker.

Cardinality: 3.