Add helper functions for FreeBSD KTLS.

Add helper functions for FreeBSD KTLS.

These are similar to the helpers added in 95badfeb60.  I've adjusted
the arguments passed to ktls_check_supported_cipher and
ktls_configure_crypto so that FreeBSD and Linux can both use the same
signature to avoid OS-specific #ifdef's in libssl.  This also required
moving the check on valid TLS versions into
ktls_check_supported_cipher for Linux.  This has largely removed
OS-specific code and OS-specific #ifdef's for KTLS outside of
<internal/ktls.h>.

Reviewed-by: Tomas Mraz <tmraz@fedoraproject.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/12111)