CORE: ossl_namemap_add_names(): new function to add multiple names

CORE: ossl_namemap_add_names(): new function to add multiple names

This was originally the private add_names_to_namemap() in
crypto/evp/evp_fetch.c, but made more generally useful.

To make for more consistent function naming, ossl_namemap_add() and
ossl_namemap_add_n() are renamed to ossl_namemap_add_name() and
ossl_namemap_add_name_n().

Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/10394)