Parent issue for Simplifying State Management

[Pothulapati]

This is a parent issue to track the current work happening on Simplifying State Management as per linkerd/rfc#35

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• Add a new linkerd-config-overrides secret
• Update the control-plane components to be able to get most configuration through
  flags, and remove the dependency on the current linkerd cm.
• Remove the generation of linkerd-config cm.
• Update the upgrade flow to use the secrets, and give it priority over the
  current linkerd-config.
• Update the check workflow to understand the current cluster state from the
  new format.
• Update Add-ons individually to have its own configuration resource, and
  update CLI for upgrades and checks accordingly.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed in 14 days if no further activity occurs. Thank you for your contributions.