[discussion] perform Operator::register when invoking Operator::start

[lburgazzoli]

As today, once you call Operator::register, then watches are put in place and the reconcile loop may chick in before the Operator::start method is invoked.

I wonder if it would be better to move the registration steps to the startup phase so the lifecycle of the operator and the controller would be predictable and consistent.

[lburgazzoli]

pr #491 may address this issues