Prepare to generalize maybe_requires_ciphersuite_enabled
Prepare to generalize maybe_requires_ciphersuite_enabled

Rename maybe_requires_ciphersuite_enabled() to detect_required_features()
and refactor its code a little. No intended behavior change. In subsequent
commits, this function will detect other requirements in a similar way.

Signed-off-by: Gilles Peskine <f805f64266d288fc5467baa7be6cd0ff366f477b@arm.com>

Mbed-TLS/mbedtls,ARMmbed/mbedtls,ARMmbed/mbedtls,ARMmbed/mbedtls,Mbed-TLS/mbedtls,ARMmbed/mbedtls,Mbed-TLS/mbedtls,Mbed-TLS/mbedtls