vfs: add context parameter to New() for config propagation

Add a ctx parameter to vfs.New() so callers can pass in context
carrying ConfigInfo and FilterInfo. The context is stripped of
cancellation but config and filter values are preserved into a fresh
background context.

cmd/mountlib/mount.go

@@ -369,7 +369,7 @@ func (m *MountPoint) Mount() (mountDaemon *os.Process, err error) {
 		}
 	}
 
-	m.VFS = vfs.New(m.Fs, &m.VFSOpt)
+	m.VFS = vfs.New(context.Background(), m.Fs, &m.VFSOpt)
 
 	m.ErrChan, m.UnmountFn, err = m.MountFn(m.VFS, m.MountPoint, &m.MountOpt)
 	if err != nil {