Motivation:
This resolves a TODO from the initial transport-native-kqueue implementation, supplying the user with the pid of the local peer client/server process.
Modification:
Inside netty_kqueue_bsdsocket_getPeerCredentials, Call getsockopt with LOCAL_PEERPID and pass it to PeerCredentials constructor.
Add a test case in KQueueSocketTest.
Result:
PeerCredentials now have pid field set. Fixes https://github.com/netty/netty/issues/9213