Users should be able to remove themselves from email suppression list via settings panel

[lsabor]

slack thread: https://metaculus.slack.com/archives/C01Q9AQBVHB/p1777475844227769?thread_ts=1771039498.868119&cid=C01Q9AQBVHB

indicate to users, on settings page, say, that editing suppression list can be solution for when they do not receive expected messages