[JN-1525] adds subject to participant list

[devonbush]

DESCRIPTION (include screenshots, and mobile screenshots for participant UX)

Adds subject to the participant list

This is hidden by default since it will only be useful for A-T and other studies with proxies

TO TEST: (simple manual steps for confirming core behavior -- used for pre-release checks)

1. go to https://localhost:3000/demo/studies/heartdemo/env/sandbox/participants
2. confirm 'subject' is not initially shown
3. Add it from the column select, confirm it appears

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[connorlbark]

Hmm... So right now the backend doesn't load proxies at all for the participant list. By default it only loads subjects. I would find this UI confusing because this will always display no proxies unless someone also goes in and edits their advanced search filters as well as this column filter.

Perhaps we should remove that automatically added search filter and instead do the filtering in the frontend. That way this column filter will work as expected.

Alternatively, we could have this column filter control whether or not that filter gets added to the search expression sent to the backend.

[devonbush]

agree with Connor's thought. We can go ahead and merge this PR to add the column, and then follow-up with a later PR to change the default filtering