Add querier to knapsack; expand osquery checkup

[RebeccaMahany]

This PR expands the osquery checkup:

• Adds instance history to the checkup, giving us the ten most recent osqueryd restarts with reasons and timestamps
• Adds an osquery extension healthcheck to the checkup -- we already run this healthcheck periodically within the osquery runner, but I thought that adding it here would give us a better snapshot of the state of osquery in one place
• Since the above tests launcher <=> osquery communication, removes the exec to launcher interactive as it's redundant
• Marks the osquery checkup as log-supported, so we can get a full snapshot of osquery state in the logs regularly

To accomplish the healthchecking, I added the querier interface into knapsack.

Relates to #1442

[directionless]

#1180 is related work, but driven using callbacks. I don't know that we need the callbacks. but I wanted to link the PRs

[RebeccaMahany]

Closing since we don't need this at the moment