fix: set directConnection true on direct connections COMPASS-4534

[Anemy]

COMPASS-4534 and fixes https://github.com/mongodb-js/compass/issues/2075

Node driver 3.6.3 introduced a change where it no longer sets directConnection on the parsed connection string for single host connections with no supplied replica set:
mongodb/node-mongodb-native@f8fd310

This PR introduces that behavior into our connect method so existing Compass connections are not broken.

Since tests in this module aren't very integrated with the driver (yet). We have some manual tests to run:
Before merging:

• Tested srv connection
• Tested connecting to a standalone
• Tested connecting directly to primary in replica set with host resolving
• Tested connecting directly to primary in replica set without host resolving
• Tested connecting directly to primary with ssh in replica set with host resolving
• Tested connecting directly to primary with ssh in replica set without host resolving
• Tested connecting directly to secondary in replica set with host resolving
• Tested connecting directly to secondary in replica set without host resolving - this fails now even with readPreference=secondary - I think it's another change we need to make
• Tested connecting directly to secondary with ssh in replica set with host resolving
• Tested connecting directly to secondary with ssh in replica set without host resolving
  We'll include an integration test for this behavior in the upcoming connectivity integration test epic.

[mcasimir]

This is why you were asking if we should make that a peer dep right? 😄

[Anemy]

Yup. I can update that in another PR though to keep things simple. (Maybe it'll require a major release?)