feat: add iwant request tracking

[wemeetagain]

Implements https://github.com/libp2p/specs/blob/master/pubsub/gossipsub/gossipsub-v1.1.md#spam-protection-measures bullet point 4

Follows go-libp2p-pubsub implementation closely

Suffers from issues related to #105
eg: in cases where a peer has signaled that they IHAVE a message, we send a IWANT, they send the message, but don't include a signature on a message when we have strict signing, the peer should be penalized twice, once for the invalid message, and once more if they fail to deliver on their promise to send the IWANTed message.
Right now, they only get the first penalty, from the invalid message.

[codecov-commenter]

Codecov Report

Merging #107 into gsv1.1 will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           gsv1.1     #107   +/-   ##
=======================================
  Coverage   91.66%   91.66%           
=======================================
  Files           2        2           
  Lines          24       24           
=======================================
  Hits           22       22           
  Misses          2        2           

Impacted Files	Coverage Δ
test/utils/index.js	81.81% <ø> (ø)

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[vasco-santos]

Overall this looks good to me. Just found some minor things that wanted to raise

[vasco-santos]

It seems that we are not using the peerID

[wemeetagain]

The idea is to have the same function signature as PeerScore#deliverMessage.
So that we might in the future abstract the different 'tracers' as in go-libp2p-pubsub
See https://github.com/libp2p/go-libp2p-pubsub/blob/master/pubsub.go#L972
Eg: they don't call each one individually:

this.score.deliverMessage(p, msg)
this.gossipTracer.deliverMessage(p, msg)
this.tagTracer.deliverMessage(p, msg)

They have some sort of registration for each of their tracers, then all tracers get called on a single call to deliverMessage.
Note the go-libp2p-pubsub tracer functionality is happening on the pubsub layer, not the gossipsub layer. Aggregating our "tracers" together would be a first step towards moving in that direction. Not saying thats what we should do, but aligning function signatures is a prereq.

[vasco-santos]

ok, sounds good

[vasco-santos]

LGTM