Allow configuring reboot delay

[dhawal55]

I'm assuming update operator is rebooting one node at a time. I would propose to allow configuring the time delay between node reboots. Locksmithd has a hardcoded rebootDelay of 5 mins but I would prefer much slower rollout of updates and want it to be configurable.

[dghubble]

It would be nice to have an option for the delay. However, the update-operator is a state machine which performs a number of coordinated actions, we can't simply sleep or it'll introduce issues down the road.

Technically, you could have a pre-reboot pod that waits for your desired period right now.