Allow for multiple generated valid referral links

Privacy-minded anons may be reluctant to share a single referral url across multiple mediums because it could be used to cross-identify them. While privacy maximalists may simply never refer, I think many people are in-between and are willing to refer but don't want that single url imprinted everywhere.

It might boost referrals and user growth if there was a button to regenerate a new referral url on-demand or if there was a “Copy Fresh Referral Link” convenience button that gave a different new referral url each time. As long as the prior older links also stay valid and continue to count referrals, this would both preserve privacy and incentivize wider referral posting.