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/premiumizeme/premiumizeme.go

@@ -770,6 +770,12 @@ func (f *Fs) PublicLink(ctx context.Context, remote string, expire fs.Duration,
 	return o.(*Object).url, nil
 }
 
+// Shutdown shutdown the fs
+func (f *Fs) Shutdown(ctx context.Context) error {
+	f.tokenRenewer.Shutdown()
+	return nil
+}
+
 // About gets quota information
 func (f *Fs) About(ctx context.Context) (usage *fs.Usage, err error) {
 	var resp *http.Response
@@ -1110,6 +1116,7 @@ var (
 	_ fs.DirCacheFlusher = (*Fs)(nil)
 	_ fs.Abouter         = (*Fs)(nil)
 	_ fs.PublicLinker    = (*Fs)(nil)
+	_ fs.Shutdowner      = (*Fs)(nil)
 	_ fs.Object          = (*Object)(nil)
 	_ fs.MimeTyper       = (*Object)(nil)
 	_ fs.IDer            = (*Object)(nil)