GitLab

* refactor: add reverse index to peerWantManager to speed up cancels

* refactor: in peerWantManager use ForEach instead of allocating lists

* fix: minimize time holding wantlist lock

Instead of holding the lock the entire time we prepare a message, hold the lock
while we retrieve the wantlist entries, process the entries without the lock,
retake the lock, then mark entries as sent.

This means:

1. We never sort entries while holding the lock.
2. We allocate exactly three times while holding the lock (once per entry list).

* fix: address code review

feat: optimize entry sorting in MessageQueue

Move connection management into networking layer

There's no reason to launch this async.

Instead of copying these slices, we can just reuse them.

refactor: simplify messageQueue onSent

feat: prioritize more important wants

In case we're sending a _lot_ of wants:

* Prioritize cancels.
* Then targeted wants.
* Finally broadcast wants.

fix: in message queue only send cancel if want was sent

* docs: add separate how bitswap works doc

* feat: update architecture diagram and add implementation description

fix: ensure wantlist gauge gets decremented on disconnect

avoid copying messages and improve logging