sign-file,extract-cert: avoid using deprecated ERR_get_error_line()

ERR_get_error_line() is deprecated since OpenSSL 3.0.

Use ERR_peek_error_line() instead, and combine display_openssl_errors()
and drain_openssl_errors() to a single function where parameter decides
if it should consume errors silently.

Signed-off-by: Jan Stancek <jstancek@redhat.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Tested-by: R Nageswara Sastry <rnsastry@linux.ibm.com>
Reviewed-by: Neal Gompa <neal@gompa.dev>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>