fix: Modify enroll:fetch response similar to enroll:list to be consistent

[sitaram-kalluri]

- What I did

• The response of enroll:fetch and enroll:list are different. Ensure the responses are consistent. Hence modified the enroll:fetch response to be similar to enroll:list command.

- How I did it

• Fetch the enrollment details from the keystore and construct a map with the fields that are to be sent to client. Convert the response to jsonEncoded string and return it back to the clients.

- How to verify it

• Updated the unit and functional tests.