scd: Add new command: KEYINFO.
* scd/app-common.h (struct app_ctx_s): Add with_keygrip function. * scd/app-openpgp.c (do_with_keygrip): New. * scd/app.c (app_do_with_keygrip): New. * scd/command.c (cmd_keyinfo): New. (send_keyinfo): New.
KEYGRIP_ACTION_LOOKUP is not yet used. It will be used for directly
asking PK* action to determine an APP.
- Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>