openssl cms: add error message if operation option is missing

If the `openssl cms` command is called without specifying an
operation option, it replies with the following laconic error message:

    cms: Use -help for summary.

This commit adds a helpful error message:

    No operation option (-encrypt|-decrypt|-sign|-verify|...) specified.

Reviewed-by: Matt Caswell <[email protected]>
(Merged from openssl#8861)

apps/cms.c

@@ -640,6 +640,7 @@ int cms_main(int argc, char **argv)
             goto opthelp;
         }
     } else if (!operation) {
+        BIO_printf(bio_err, "No operation option (-encrypt|-decrypt|-sign|-verify|...) specified.\n");
         goto opthelp;
     }