Use a table for the smart card keys

This is basically a rewrite of the UI for displaying the smart card keys and the associated certificates and for interacting with the smart card keys/card slots.

There is still a bit to clean up, e.g. most cards (sometimes) show some additional UI elements between the two common Card type and Serial number labels and the table.

See https://dev.gnupg.org/T7018 for screenshots of new (and old) UI.

@carlschwan @tfella Comments are welcome