Imitate zpool clear
We were setting a different key ("rewind-request") for rewind policy for clearing errors for a given pool. We should fix this issue and copy the behaviour from zpool_main where we use ("load-rewind-policy").
We risk breaking ZFSPool's clear method which is used to clear a pools errors
We can use zinject to inject errors in zfs and then use zfspool's clear method to see if that clears the issues in the pool.