A test for tags has been restructured so that more parts of it can
easily be run on a platform without a working GnuPG.
* es/test-gpg-tags:
t6302: skip only signed tags rather than all tests when GPG is missing
t6302: also test annotated in addition to signed tags
t6302: normalize names and descriptions of signed tags
lib-gpg: drop unnecessary "missing GPG" warning