Add 2FA requirement

[mpadge]

@maelle This could be included as a pkgcheck on submission. It's easy to include internal-only checks that are only triggered when called by the bot, so a pkgchk_author_has_2fa would be ignored except for our purposes, and submissions would only proceed once 2FA had been set up. Do you see any problems with that?

[maelle]

Thanks, I can see the advantages but

• We can't know whether someone has enabled 2FA.
• It'd seem unethical to make that info public.

So actually it could be a check but only if run locally, by the maintainer?