[#2396] Allow to set TCP_KEEPIDLE, TCP_KEEPINTVL and TCP_KEEPCNT in nati...

...ve transport

Motivation:
Allow to set TCP_KEEPIDLE, TCP_KEEPINTVL and TCP_KEEPCNT in native transport to offer the user with more flexibility.

Modifications:
Expose methods to set these options and write the JNI implementation.

Result:
User can now use TCP_KEEPIDLE, TCP_KEEPINTVL and TCP_KEEPCNT.