Background

Currently we determine the direction of migration by checking what the spec.authoritativeAPI.

This works for the base case, but it doesn't work when a migration is stuck in .status.authoritativeAPI: Migrating and the user, to unblock the migration, changes the .spec.authoritativeAPI back to the original value.

At that point we need to reliably tell which way we were trying to migrate to when we got stuck. That will allow us to then be able to exactly tell which API engine to roll back to and to apply the rollback procedure to undo the partial migration. 

So we want to add a `.status.synchronizedAPI` field (with possible values as "" | MachineAPI | ClusterAPI) on both MAPI MachineSet and MAPI Machine. 

Steps

• Add .status.synchronizedAPI of Machine API resources based on the enhancement
• Adding setting the field in the sync controllers and in the migration controllers logic
• Get API review
• Get API merged

Stakeholders

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Definition of Done

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• Docs

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• Testing

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