Add RSA Signature restrictions for X9.31 padding in the FIPS provider.

Add RSA Signature restrictions for X9.31 padding in the FIPS provider.

In FIPS 140-3, RSA Signing with X9.31 padding is not approved,
but verification is allowed for legacy purposes. An indicator has been added
for RSA signing with X9.31 padding.

A strict restriction on the size of the RSA modulus has been added
i.e. It must be 1024 + 256 * s (which is part of the ANSI X9.31 spec).

Added implementation comments to the X9.31 padding code

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Paul Dale <ppzgs1@gmail.com>
(Merged from https://github.com/openssl/openssl/pull/24021)