Add diagnostic logging to GetFileStreamException catch block

The GetFileStreamException catch in GetFileStreamHandlerAsyncHandler
silently completed the ProjFS command without logging requestMetadata
(SHA, virtual path). Other catch blocks in the same handler all log
this metadata. Add a RelatedWarning with the HResult value for
diagnostic visibility while keeping the severity appropriate for
expected/benign HResult.Handle results.

Assisted-by: Claude Opus 4.6
Signed-off-by: Tyrie Vella <tyrielv@gmail.com>

Author: tyrielv

GVFS/GVFS.Platform.Windows/WindowsFileSystemVirtualizer.cs

@@ -981,6 +981,9 @@ private void GetFileStreamHandlerAsyncHandler(
             }
             catch (GetFileStreamException e)
             {
+                requestMetadata.Add(TracingConstants.MessageKey.InfoMessage, $"{nameof(this.GetFileStreamHandlerAsyncHandler)}: GetFileStreamException HResult 0x{e.HResult:X8}");
+                this.Context.Tracer.RelatedWarning(requestMetadata, nameof(this.GetFileStreamHandlerAsyncHandler) + "_GetFileStreamException");
+
                 this.TryCompleteCommand(commandId, (HResult)e.HResult);
                 return;
             }