The stats output gave no way to tell which RIST profile a flow used or
whether Advanced framing was active on the wire. Add `profile` and
`advanced_active` to the sender peer stats, and `profile`, `seq_bits`, and
`advanced_active` to the receiver flow stats, with matching fields in the
JSON payloads. Bump RIST_STATS_VERSION to 3 and the JSON schema version to 4.
The Prometheus exporter emits new `rist_client_flow_info` and
`rist_sender_peer_info` series that carry these as labels, so a scrape can
identify an Advanced flow (and 16-bit vs 32-bit framing) without changing the
label set of the existing series. On the sender, advanced_active reflects
whether Advanced framing is in use toward the peer; on the receiver flow it
is true only when the context is Advanced and the flow is on 32-bit framing,
so it reads false when an Advanced context stays on Main framing because the
peer has not advertised Advanced support (TR-06-3 Section 9) and false for
Main and Simple contexts.
Sergio Ammirata
4d55974da5