cms demos: print signingTime attributes
Add a makefile for the cms demos, and add a routine to cms_ver.c to
print any signingTime attributes from the CMS_ContentInfo object.
This provides an example that could be extended if an application
wants to examine the purported signing times.
Part of #8026
Testing:
$ cd demos/cms
$ make test
Reviewed-by: Shane Lontis <shane.lontis@oracle.com>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(cherry picked from commit
9257a89b6f25dfa5aeee7114baec8ea992fcf5e5)
Reviewed-by: Hugo Landau <hlandau@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/22728)