--max-transfer - add new exit code (10)

It adds dedicated exit code (10) for --max-duration flag.

Rclone will exit with exit code 10 if the duration limit is reached.

It behaves in similar fashion as --max-transfer and exit code 8.

discussed on the forum:

https://forum.rclone.org/t/max-duration-option-is-triggering-exit-with-error/39917/6

fs/sync/sync_test.go

@@ -996,7 +996,7 @@ func testSyncWithMaxDuration(t *testing.T, cutoffMode fs.CutoffMode) {
 	accounting.GlobalStats().ResetCounters()
 	startTime := time.Now()
 	err := Sync(ctx, r.Fremote, r.Flocal, false)
-	require.True(t, errors.Is(err, errorMaxDurationReached))
+	require.True(t, errors.Is(err, ErrorMaxDurationReached))
 
 	if cutoffMode == fs.CutoffModeHard {
 		r.CheckRemoteItems(t, file1)