backend: fs implements the Shutdowner interface

Since `tokenRenewer` adds a Shutdown method, we should call it to
clean up resources.

changes backends:
onedrive,box,pcloud,amazonclouddrive,hidrive,jottacloud,sharefile
,premiumizeme

Signed-off-by: rkonfj <rkonfj@gmail.com>

backend/amazonclouddrive/amazonclouddrive.go

@@ -1346,6 +1346,12 @@ func (f *Fs) changeNotifyRunner(notifyFunc func(string, fs.EntryType), checkpoin
 	return checkpoint
 }
 
+// Shutdown shutdown the fs
+func (f *Fs) Shutdown(ctx context.Context) error {
+	f.tokenRenewer.Shutdown()
+	return nil
+}
+
 // ID returns the ID of the Object if known, or "" if not
 func (o *Object) ID() string {
 	if o.info.Id == nil {
@@ -1363,6 +1369,7 @@ var (
 	_ fs.DirMover        = (*Fs)(nil)
 	_ fs.DirCacheFlusher = (*Fs)(nil)
 	_ fs.ChangeNotifier  = (*Fs)(nil)
+	_ fs.Shutdowner      = (*Fs)(nil)
 	_ fs.Object          = (*Object)(nil)
 	_ fs.MimeTyper       = &Object{}
 	_ fs.IDer            = &Object{}