Add Cron Monitoring for the Scheduler Component

[cleptric]

Symfony 6.3 added a new Scheduler Component, something we should add support for, for Cron Monitoring.

https://symfony.com/blog/new-in-symfony-6-3-scheduler-component

[Mika56]

Hello,

I am interested in using and implementing this feature as well.

Scheduler seems to have everything we need to implement this, the most important being that Scheduler dispatches events before and after running crons.

Questions that come to mind are:

• How/when are crons definitions sent to Sentry? I think it could be either:
  • A dedicated sentry:crons:sync-definitions command
  • Anytime a Messenger worker is started (my preference)
• How do we set checkinMargin, maxRuntime, failureIssueThreshold, recoveryThreshold? I suggest we add a #[Sentry\Cron] attribute or similar