Adds a package for testing time/timer/ticker functions. Implementation is limited to `NewTimer` and `NewContextTicker`, but will eventually be expanded to all `time` functions from the standard library as well as `context.WithTimeout()`, `context.WithDeadline()`.
Replaces `benbjohnson/clock` for the pubsub watchdog, as a proof of concept.
Eventually, as we expand functionality, we will replace most time-related functions with this library for testing.
Fixes#12030
This is a good example of the kind of thing I'd like to address with a time-testing lib. The problem is that there is a race between the watchdog starting it's timer and the test incrementing the time. What would make this easier is if the time-testing library could wait for and assert the call to start the timer before incrementing the time.
adds a watchdog to our pubsub and runs it for Coder server.
If the watchdog times out, it triggers a graceful exit in `coder server` to give any provisioner jobs a chance to shut down.
c.f. #11950
