tests: add test cases for import without uid

This commit adds a test case that does the following, in order:

• Import of a primary key plus user id
• Check that import of a subkey works, without a user id present in the

imported key

• Check that import of a subkey revocation works, without a user id or

subkey binding signature present in the imported key

• Check that import of a primary key revocation works, without a user id

present in the imported key

Note that this test currently fails. The following changesets will
fix gpg so that the tests pass.

Gbp-Pq: Topic import-merge-without-userid
Gbp-Pq: Name tests-add-test-cases-for-import-without-uid.patch

• GnuPG-Bug-id: T4393
• Signed-Off-By: Daniel Kahn Gillmor <dkg@fifthhorseman.net>