vfs: convert vfs options to new style

This also
- move in use options (Opt) from vfsflags to vfscommon
- change os.FileMode to vfscommon.FileMode in parameters
- rework vfscommon.FileMode and add tests

cmd/serve/http/http.go

@@ -24,6 +24,7 @@ import (
 	"github.com/rclone/rclone/lib/http/serve"
 	"github.com/rclone/rclone/lib/systemd"
 	"github.com/rclone/rclone/vfs"
+	"github.com/rclone/rclone/vfs/vfscommon"
 	"github.com/rclone/rclone/vfs/vfsflags"
 	"github.com/spf13/cobra"
 )
@@ -148,7 +149,7 @@ func run(ctx context.Context, f fs.Fs, opt Options) (s *HTTP, err error) {
 		// override auth
 		s.opt.Auth.CustomAuthFn = s.auth
 	} else {
-		s._vfs = vfs.New(f, &vfsflags.Opt)
+		s._vfs = vfs.New(f, &vfscommon.Opt)
 	}
 
 	s.server, err = libhttp.NewServer(ctx,
@@ -215,7 +216,7 @@ func (s *HTTP) serveDir(w http.ResponseWriter, r *http.Request, dirRemote string
 	// Make the entries for display
 	directory := serve.NewDirectory(dirRemote, s.server.HTMLTemplate())
 	for _, node := range dirEntries {
-		if vfsflags.Opt.NoModTime {
+		if vfscommon.Opt.NoModTime {
 			directory.AddHTMLEntry(node.Path(), node.IsDir(), node.Size(), time.Time{})
 		} else {
 			directory.AddHTMLEntry(node.Path(), node.IsDir(), node.Size(), node.ModTime().UTC())