Add ThrottlingListener to allow MFA attempt throttling

[tostiheld]

Trying again after I forgot about #165 😄

Still in draft, because I'm still working on tests, but I thought I would already put something up because of #SymfonyHackday

This basically does the same thing as the previous PR, with one notable improvement. I agree with the point that @hdk-pd made previously (#165 (comment)). Therefore I took some inspiration from symfony/symfony#38308 and implemented a combined ratelimiter instead of a single one. It will now ratelimit on both IP and user identifier.

[scheb]

Thanks for the effort. We recently figured in #208 that the login_throttling feature on the firewall-level adds this behavior out-of-the-box, not only for the initial login, but also for the 2fa.

[tostiheld]

Okay, I will close this.