fix(tests): stabilize session tests

[hannahhoward]

Goals

Improve stability of tests for Session and SessionPeerManager so that CI consistently passes

Implementation

Basically, tests of concurrent code is hard. Definitely don't want to deadlock, and also, want to make sure synchronization is correct so that work is always done before results are tests

With that in mind:

• make channel read/writes select statements
• Change ordering for channel reads in TestSessionFindMorePeers -- this was the issue -- the cancel wants channel is actually the first thing that needs to be read. And, additional fix for Windows where apparently timing is very imprecise. (time: NewTimer & NewTicker should use SetWaitableTimer on Windows golang/go#29714)
• Additional channels and syncing for SessionPeerManager tests -- not that much of the complexity here goes away when Feat: A more robust provider finder for sessions (for now) and soon for all bitswap #60 is merged, and is indicative of the current code being too complex for a single class

For Discussion

fix #61