[PATCH v2 GnuPG] allow import without user ids

[Vincent Breitmoser]

I included dkg's testing series, as expected the test only passes once the
second patch is applied.

Only three out of five of dkg's files are currently used: import of subkey
revocations that have no binding signature, as well as out-of-place user id
signatures,  is out of scope for this patch. I included the others anyways,
since may be userful later on (without regenerating the whole series).

I also noticed that the way I handled invalid uids before didn't make much
sense: just because there is some invalid uid in a key, doesn't mean
cryptographically valid new packets can't be imported. I changed the patch to
reflect that.

Signed-Off-By: Vincent Breitmoser <look at my.amazin.horse>