Abstract Proof of Humanity from Passport app

This story is to break down this parent [ticket](https://github.com/gitcoinco/passport/issues/607) to smaller issues.. The goal is the same, but to abstract just this single platform from passport.

For further details:
https://github.com/gitcoinco/passport/issues/607

Start by reading the parent ticket, issue #607, for the requirements and scope of abstracting Proof of Humanity from the Passport app. Identify the smaller implementation boundary described there; the work is done when this platform is abstracted as a separate, actionable component of that goal.

Written by the indexing model from the issue text.