Refactor the devise-two-factor integration to use turbo streams

[jagthedrummer]

In this discussion @pascallaliberte said:

Real quick, I'm thinking a slightly larger refactor is recommended. It's probably worth:

1. replacingcreate.js.erb and other ujs js responses with a turbo response. I'm thinking responding with a turbo-stream update (not replace) of #two-factor's internals using the contents of the devise/registrations/two_factor
2. replacing the two link_to's in _two_factor.html.erb with button_to to create small proper forms, which will return a turbo_stream as in step 1