Move ssl_err.c into libcrypto

Move ssl_err.c into libcrypto

We move ssl_err.c out of libssl and into libcrypto. This file is entirely
self contained and is used to load error strings into the libcrypto error
tables. By moving this file into libcrypto, libssl can be unloaded safely
without having dangling references to this error information.

Fixes #26672

Reviewed-by: Neil Horman <nhorman@openssl.org>
Reviewed-by: Saša Nedvědický <sashan@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Tim Hudson <tjh@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/26931)