Improve Subject - sample CSV file

[shraddha761]

Acceptance Criteria

Sample CSV file to be downloaded: Link

Headers should be populated on the basis of configured values as mentioned below.

1. 'Profile Picture' Url/link that points to image.
2. Id, First Name and rest of filed header should be same as mentioned in sample csv file.
   3 .'Sync Attribute' header should be populated in the sample CSV in case that is part of the UI for any project. (Should not be populated
   in CSV if not available in UI for any project)

[vinayvenu]

avniproject/avni-server#823