The order of entries in a dictionary is not specified by the JSON
standard and hard to control when marshalling dictionaries in Go.
Since the order of mounts is important and the wrong order leads
to wrong mount trees change the `mounts` field to an array. This
breaks existing manifests but after careful deliberation it was
concluded that the original schema with mounts as dictionaries
is not something we want to support. Apologies to everyone.
Adjust the schema of the copy and zipl stage accordingly.
ae1296e33a