Support no-touch-required security key (e.g. ecdsa-sk)

In contrast to the comment #213259 (comment 827207788) given in another issue, I want to point out that even a no-touch-required security key backed ssh key is still a major improvement over using a "normal" ssh key. The no-touch-required can not be simply copied/"stolen", i.e. only works if the corresponding key is present in the machine.

I do not object that it would be way more secure to require an interaction. However, requiring an interaction for each remote action can be a major showbreaker imho. Therefore, it would be nice to have the additional option of no-touch-required keys. (Allowing to have keys which require interaction and others which do not)

This option would not distrubt the current user flow and also allow some batch/automation on the user machine as long as the security key is connected.