Make PipePosix to support next operations:
- Create a named pipe.
- Open reader and writer sides of a named pipe.
- Timeout-based Read and Write operations.
- Added Delete call to PipeBase interface since named pipe removal differs for POSIX and Windows pipes.
Integrated Pipe class into GDBRemoteCommunication::StartDebugserverProcess and lldb-gdbserver in order to support reading and writing a port value to a named pipe.