Automatically generate an anonymous_id different from the email address

When a user signs up (for example in a newsletter form with only the email field), generate a unique id to be used as an identifier instead of the email address. The id could be an hashed version of the email address. This way we could mask the email address on confirmation links (see https://dsh.re/e1ebe3 from the "Setting up a double opt-in to manage user consent" guide, https://www.getvero.com/tutorials/setting-up-double-opt-in-manage-consent) and avoid displaying it in plain text on the browser bar, something that bothers many users.