Surface edit/delete upon key upload

In general the sign up flow was great, really well done. You guys nailed it.

The only snag was determining the right fingerprint hash from the `gpg -K --keyid-format long --with-colons --with-fingerprint` command. This is totally not your fault, but rather a (serious I think!) usability flaw with gpg's output format. I will take this up with them

But the issue led to my accidentally exporting the wrong key, for a different email address than I'd intended. Maybe there could be an easier-to-find way to upload a different key. I see that there's a way to edit/delete the key from the utility menu, but it took me a little while to discover that. Maybe right after the upload that option could be surfaced more prominantly.

Start by reviewing the sign-up key-upload flow and the utility menu where edit/delete actions are currently found. The change is complete when users can readily find a way to edit or delete the uploaded key immediately after upload, including replacing an accidentally selected key.

Written by the indexing model from the issue text.