The previous error `UnexpectedState` was opaque, and ended up in a
confusing message when a user would try to edit the identity document
while not being a deleagte themselves.
Instead, provide a more specific error that mentions the `Did`
performing the action, and the action itself.
Note that the `UnexpectedState` variant was matched on during
evaluation, meaning that operations would still appear in the timeline
of the COB. With the change to the other variant, the timeline does
not record the operation anymore.
67a4a712e4