kbx: Add framework for the SEARCH command
* kbx/backend-kbx.c: New. * kbx/backend-support.c: New. * kbx/backend.h: New. * kbx/frontend.c: New. * kbx/frontend.h: New. * kbx/kbxserver.c: Implement SEARCH and NEXT command. * kbx/keybox-search-desc.h (enum pubkey_types): New. * kbx/keybox-search.c (keybox_get_data): New. * kbx/keyboxd.c (main): Add a standard resource.
- Signed-off-by: Werner Koch <wk@gnupg.org>