Gossip: add peer score tracking ability

[Nashatyrev]

Description

Would be good to have a mechanism to track and explain peer gossip score

Motivation

A peer may loose its mesh due to downscore and we basically have no idea what's going on with a peer score.
https://hackmd.io/fumYP6OKTLSin6dAVSI-9A

Requirements

The first idea which comes to mind is to emit peer score snapshot (immutable) every decayInterval. The snapshot should include both the sore values (including all topics) and original counters (like meshDeliveries, firstDeliveries) for better context. The client may want to subscribe to these snapshots and log some explanation whenever the score drops below some threshold(s)

However there are cases when the score should be updated earlier than at the end of decayInterval, for example invalidMessages when we need to react faster to avoid DoSing with invalid messages for a longer period.

Open questions

No response

Are you planning to do it yourself in a pull request ?

Maybe