Add hidden command to set bucket encryption key to fix HDDS-7449

Through this patch, we can reset the encryption of a bucket through ozone shell (ozone sh bucket set-encryption-key -k <enckey> <vol>/<buck>).

It does not change any other properties of the bucket or the existing keys in the bucket. The newer keys added to the bucket are encrypted using the same BEK details provided - the fileEncryptionInfo object on the key level gets generated as expected.