EVP: Add support for comparing provided EVP_PKEYs

EVP: Add support for comparing provided EVP_PKEYs

This adds evp_keymgmt_util_match() and affects EVP_PKEY_cmp() and
EVP_PKEY_cmp_parameters().

The word 'match' was used for the new routines because many associate
'cmp' with comparison functions that allows sorting, i.e. return -1, 0
or 1 depending on the order in which the two compared elements should
be sorted.  EVP_PKEY_cmp() and EVP_PKEY_cmp_parameters() don't quite
do that.

Reviewed-by: Shane Lontis <shane.lontis@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/11158)