[edit] No duplicate detection when editing details

[GZTan23]

Description:

The Student ID and NUSNET ID are able to be edited, but there is no detection of a duplicate contact in place

Steps to Reproduce:

• Execute edit command to edit the NUSNET ID and Student ID to be the same as another contact in the list

Expected Behavior:

Duplicate contact error

Observed Behavior:

Successful execution

Screenshot(s):