This change corrects verification of certifications over User Attributes
(such as photos).
Before this change the code did not differentiate between User IDs and
User Attributes as both of them were stored in `data.userid` [0] and
incorrectly used the User ID constant (0xB4) for both cases.
This change fixes the bug by storing User IDs in `userId` property and
User Attributes in `userAttribute` property. The check for property
existence has been modified to avoid comparisons with `undefined` as the
`User` class sets `null` for not assigned packets instead of
`undefined`.
Only data structures for signing and verification were modified and not
the properties used in the `User` class.
[0]: 11b2d2de3c/src/key.js (L872)
During tests of weird keys [0] it was found out that OpenPGP.js does not
handle keys without valid UIDs well.
There are two issues that this change corrects, first one is adding
filtering of user IDs in `getPrimaryUser` such as only users with self
certifications are considered. Without that change using
`getPrimaryUser` on a key without valid UIDs would throw an exception
(`Cannot read property 'verified' of undefined` [1]).
Second issue is correcting condition whether to throw if no UID was
found. Previous condition checked for `userId` variable, but this is
initialized by default and as such is almost always set. This causes
`key.getPrimaryUser()` (without condition) to throw `Could not find user
that matches that user ID`. The condition has been modified to match the
filter condition (checking if any property of `userId` has been
initialized).
[0]: https://gitlab.com/sequoia-pgp/weird-keys/tree/master/openpgpjs
[1]: 576ed08a54/openpgpjs/results/no-bound-uid.pgp.txt
