Go blocking reads can't be interrupted by closing the fid from another
thread. Revert to subprocess-based streaming using ollie-9p, which can
be killed cleanly.
Native library is still used for all request/response operations.
Only streaming (chat, statewait, eventwait) uses subprocess.
Replace StreamFsm and NinePConnection (QProcess-based) with NativeStreamer
which uses the new libollie9p streaming API (open/read_fid/close_fid).
All 9P operations now go through the native library:
- Chat, statewait, eventwait streams use threaded NativeStreamer
- Request/response operations use Lib9pClient directly
- No more subprocess spawning for any 9P operation
Remove ninepBin, ollie9pBin, serverAddr, run9p helper functions.
Remove streamfsm.cpp/h, ninepconnection.cpp/h from build.