Global DryRun for Application Controller

[speedfl]

Summary

ApplicationSet controller supports dryRun

It could be nice to have equivalent feature that does not perform sync operation. In my mind its equivalent of disabling autosync for all applications, but maybe I forgot something (feel free to enrich this issue)

Motivation

When doing argocd upgrade or major changes at infra level, adding a dry run really helps to oberve what actions will be performed.

Proposal

• Add dryRun parameter in application controller command
• Propagate this parameter to the appcontroller
• Run only the dryRun and exit before doing the real sync