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/sharefile/sharefile.go

@@ -1176,6 +1176,12 @@ func (f *Fs) DirCacheFlush() {
 	f.dirCache.ResetRoot()
 }
 
+// Shutdown shutdown the fs
+func (f *Fs) Shutdown(ctx context.Context) error {
+	f.tokenRenewer.Shutdown()
+	return nil
+}
+
 // Hashes returns the supported hash sets.
 func (f *Fs) Hashes() hash.Set {
 	return hash.Set(hash.MD5)
@@ -1466,6 +1472,7 @@ var (
 	_ fs.Copier   = (*Fs)(nil)
 	// _ fs.PutStreamer     = (*Fs)(nil)
 	_ fs.DirCacheFlusher = (*Fs)(nil)
+	_ fs.Shutdowner      = (*Fs)(nil)
 	_ fs.Object          = (*Object)(nil)
 	_ fs.IDer            = (*Object)(nil)
 )