GODRIVER-1489 Implement streaming heartbeat protocol

[divjotarora]

This includes the changes for reducing race conditions in SDAM error handling because that work hasn't been merged into master. Once GODRIVER-1572 is closed, I'll rebase and force-push to this PR.

[divjotarora]

The most recent commit removes the code that updated the topology based on application connection handshakes. The SDAM spec actually says drivers SHOULD use handshake responses for application connections to update the topology (https://github.com/mongodb/specifications/blob/master/source/server-discovery-and-monitoring/server-monitoring.rst#clients-update-the-topology-from-each-handshake), but most drivers don't do this and it requires additional complexity to update the RTT monitor as well.

@ShaneHarvey @jyemin Thoughts on making that a "MUST NOT" in the spec instead?

[ShaneHarvey]

I agree drivers should not update the topology from (successful) application connection handshakes. I just opened https://jira.mongodb.org/browse/DRIVERS-1300.

[divjotarora]

I did a large rebase to get the changes from some connection pool-related bugfixes and also GODRIVER-1572 (reduce race conditions in SDAM error handling). Confirmed tests pass locally, but any Evergreen failures could be related to that.

[iwysiu]

lgtm with spelling fix