JFR events SocketReadEvent/SocketWriteEvent for Socket adaptor ops

For SocketChannelImpl, the JFR events SocketReadEvent and SocketWriteEvent are supported only in the read/write and scattering/gathering read/write. I/O with the socket adaptors or via FileChannel.transferTo (think sendfile from file to socket) aren’t currently supported. These code paths need to be modified to generate the JFR events.