[wedamija]

Part of a series adding automatic Crons monitoring for the most-used job schedulers in each SDK. Check-ins for a monitor that doesn't exist yet are dropped, so today each monitor has to be created by hand with its schedule copied from the code. Sending the job's schedule as the monitor config lets Sentry create the monitor and keep it in sync.

This adds a :resque_scheduler patch to sentry-resque that sends check-ins for every resque-scheduler cron and every schedule, static or dynamic. Each schedule name becomes a monitor slug, and the schedule and its time zone are sent as the monitor config. The check-ins wrap the job's run on the worker.

config.enabled_patches << :resque_scheduler
config.resque.exclude_scheduled_jobs = ["clear_cache", /^tmp_/]

Schedules Crons can't express, like every 10 seconds, check in without a config. With the :rufus_scheduler patch from #3110 also on, resque-scheduler's jobs are reported once, by this patch.

The patch is off by default. resque-scheduler is added as a dev dependency for the specs.

Stacked on #3141.

[linear-code]

RUBY-235