[ENHANCE] ArgoCD "restart" instead of starting a new rollout for blue/green.

[im-aIex]

Is your feature request related to a problem? Please describe.
When using long-lived / manual blue/green rollouts it currently creates a new green rollout and requires time / manual intervention to make it to the blue pods. Having the option to run a "restart" would allow all pods in an existing blue/green rollout to be recreated and still maintain HA.

Describe the solution you'd like
Add an option (annotation/strategy) to run a "restart" instead of just causing an update that forces a new rollout.

Additional context
See Restarting Rollout Pods for more details.

Both of these mechanisms updates the Rollout's .spec.restartAt to the current time in the form of a RFC 3339 formatted UTC string (e.g. 2020-03-30T21:19:35Z), which indicates to the Rollout controller that all of a Rollout's Pods should have been created after this timestamp.