Update Endpoints to Fetch Display Name

[harshkhandeparkar]

After #164 is completed, all the public endpoints should be updated to only fetch the username and display name of each mentor/student.

[deepali-kumari-iitp]

Hi,
I’d like to work on this issue if it’s still available.
I can convert the project status field to an integer type and ensure the API handles it correctly.
Please assign this issue to me.
Thank you!