Have determine_ownership() method return an error in more cases
Have determine_ownership() method return an error in more cases

It now returns an error if there was an error reading the static header.
This means that it found something that looked like a Stratis device, but
it couldn't properly read its header.

Call sites all seem to be using it correctly with new meaning.

Signed-off-by: mulhern <7b51bcf507bcd7afb72bf8663752c0ddbeb517f6@redhat.com>

mulkieran/stratisd,stratis-storage/stratisd,mulkieran/stratisd,trgill/stratisd,trgill/stratisd,stratis-storage/stratisd,stratis-storage/stratisd