Add support for statusline and uidcomment

This adds support to put a custom statusline and a uidcomment in the default openpgp key generation dialog.

I am aware that this can be bypassed by adding a user id explicitly without such a uidcomment but it can also be bypassed by using GnuPG on the command line. It is not really a security feature, more of a slight marker that a key was originally created with a version where we left a uidcomment by default to indicate that the key was created with a version that might have restricted support and should not be used forever.

GnuPG-Bug-Id: T6797