Let ksba_cms_identify detect the new OpenPGP keyblock content.

* src/ksba.h.in (KSBA_CT_OPENPGP_KEYBLOCK): New.
* src/cms.c: Add to table.
* tests/t-cms-parser.c (one_file): Ditto.

This is just some basic support to provide useful diagnositics for
a data object we store on the OpenPGP card.

• Signed-off-by: Werner Koch <wk@gnupg.org>