[idd] helper/PipeClient: use event and async I/O to interrupt read

An event, `m_signal`, is created and signalled when either `m_running` or
`m_connected` is changed by another thread, so that the pipe thread knows
to interrupt the read.

The pipe is now opened as async to allow interruption, and the I/O
operations now use overlapped I/O.

Other changes include:
* Changing `m_pipe` to `HandleT<HANDLETraits>` since `CreateFile` returns
  `INVALID_HANDLE_VALUE` instead of `NULL` on error.
* Remove the call to `WaitNamedPipeA` because it's useless and returns
  immediately without waiting if the pipe doesn't exist.

idd/LGIddHelper/CPipeClient.h

@@ -1,4 +1,4 @@
-/**
+/**
  * Looking Glass
  * Copyright © 2017-2025 The Looking Glass Authors
  * https://looking-glass.io
@@ -33,8 +33,10 @@ using namespace Microsoft::WRL::Wrappers::HandleTraits;
 class CPipeClient
 {
 private:
-  HandleT<HANDLENullTraits> m_pipe;
+  HandleT<HANDLETraits> m_pipe;
   HandleT<HANDLENullTraits> m_thread;
+  HandleT<EventTraits> m_signal;
+
   bool m_running = false;
   bool m_connected = false;