Support importing/exporting identity files

[dovholuknf]

It's possible that I could use a CLI tool and enroll an identity. Once I've done that the identity will reside on my machine but I have no easy way of importing the file into the ZDEW. Support importing an identity file into the ZDEW by allowing a user to supply the identity file to import.

Also support exporting identities as well. If you are moving, upgrading, trying to backup your identities etc - right now there is no way for a user to be able to export identities.

For both operations - verify that this operation is only allowed by an "Authenticated User" with the expectation that this would be refined and made more granular than that in the future