Add field into handshake params
Add field into handshake params

Add `extensions_present` field. It represents
which are present.

Signed-off-by: Jerry Yu <c6cd1413a9492a82cc7fe506fb3a273f7dc9927d@arm.com>

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