Added SIGTERM handler for linux and closed session when reading error is caught

[CihatAltiparmak]

Addresses #251

I have no chance to try it in windows machine. but seems windows handles all signals in one handler function.

[Yadunund]

Thanks for the enhancement! Left a minor comment to consider

[CihatAltiparmak]

I'm ready for second review @Yadunund , but i want to mention just one point. If i don't remove perror in router executable, terminal looks like below when i send SIGTERM to ros2 (assuming that executes ros2 run rmw_zenoh_cpp rmw_zenohd)
. But the relavant processes are closed. This behavior is not related to my branch.

[Yadunund]

Thanks for iterating so quickly!