feat(gossipsub): support version 1.2.0

[diegomrsantos]

• Support GossipSub 1.2 in the code
• Add utility template template exclIfIt*[T](set: var HashSet[T], condition: untyped)
• Renaming

closes #1102

[kaiserd]

addresses issue #1102

[diegomrsantos]

This PR depends on this being fixed #1115, if we want to send idontwant only to peers that support 1.2.

[diegomrsantos]

• Send idontwant only to peers that support GossipSub 1.2

This will be moved to a new PR cause of #1115.

[lchenut]

I'm not an expert on GS by any means, but I'm expecting something like if GossipSubCodec_12 in g.codecs: # do something GS1.2 related. From what I understand, we just add the codecs (which needed to be done) but there's no difference between GossipSubCodec_10, GossipSubCodec_11 and GossipSubCodec_12.

[diegomrsantos]

I'm not an expert on GS by any means, but I'm expecting something like if GossipSubCodec_12 in g.codecs: # do something GS1.2 related. From what I understand, we just add the codecs (which needed to be done) but there's no difference between GossipSubCodec_10, GossipSubCodec_11 and GossipSubCodec_12.

I believe g.codecs are the versions supported by the current code, instead of the one negotiated with the peer - pubsubpeer.codec. Behaving like 1.2 - sending idontwant - will be implemented in a new PR as mentioned here: #1106 (comment).

It seems that our current code can negotiate 1.0 but will still behave like 1.1, as there's no check on how the protocol should behave depending on the version negotiated with a remote peer.

[AlejandroCabeza]

What happens if dialing 1.2.0 fails? Should we attempt to dial with a lower version?

[diegomrsantos]

This is only for tests. Production code tries all versions.