Call handlers by time

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Expected Behavior

Some of the handlers must be called regularly on the schedule (e.g. cron-like).

For example, to monitor the actual state of the system (as changed out of scope of the operator) with the declared state (as in the yaml files).

Actual Behavior

Only the objects changes cause the handlers execution.

The objects are not always changed when something else (unmonitored) happens in the cluster.

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Docs:

• https://kopf.readthedocs.io/en/latest/daemons/
• https://kopf.readthedocs.io/en/latest/timers/