Find a smart way for VC lookup

[maskit]

Currently QUICNetVConnections are stored into a Map but it has to be replaced with something else since Map is not thread safe and accessing with a lock would be too expensive.

[zizhong]

How about a multi thread safe hash table?
If it sounds good to you, I can implement it as recently I'd like to get my hands dirty with QUIC.

[maskit]

That sounds good to me. The map will be looked up on every packets, so it has to be super fast.

@bryancall Thoughts?

[SolidWallOfCode]

We've looked at Concurrency Kit before as an option. TBB has been suggested as well. This kind of thing is hard to get right, we should use a validated implementation if possible.

[maskit]

Resolved with #3055