Allow methods priorization / selection of fallback method

[adlerweb]

At the moment a user is only able to specify a primary authentication method. If the user now accesses the page using a unsupported system (for example U2F + vanilla Firefox) the plugin selects the first enabled method as fallback. As far as I can tell there is atm no way for the user to choose which method to use for fallback without disabling everything else. For me this automatically reverts to E-Mail while I would prefer Google Authenticator as a fallback (while keeping e-mail as a manual option).

[georgestephanis]

It's not something that I think is great enough of a need to add a visible administrative option for, but I wouldn't necessarily object to a filter or the like.

We may wind up sorting the methods by most recently used, rather than have any sort of user selection of primary/secondary -- so whenever a method is used, it bubbles to the top of the list, and the unused ones naturally sort themselves down to the end.

[crstauf]

Could the methods be dragged and dropped into the desired order? That seems intuitive and simple...?

Methods being sorted by most recent use seems strange... if I want U2F => OTP => email => verification codes, I've to login using each one in reverse order. I do like this behavior if the user hasn't specified an order yet.