Enable adding PoRs by General Secretaries

[ydidwania]

In the long term, we'd like to give Edit Body permission for every Institute Body to only gsectech and similar ldap ids. They will then have the option to add their subordinates .

All subordinate PoRs should be reset on April 1, when the next tenure starts

[pulsejet]

Backend already has this permission model, i.e. allowing adding roles of bodies. Probably need a better API for this though.