Breaking change: Add ScanSchedule, allows interval and cron based configurations.

See https://pkg.go.dev/github.com/robfig/cron#hdr-CRON_Expression_Format for expression syntax.

`ScanInterval` will still work for the time being. The only situation it does not work is when you want to disable periodic scanning by setting `ScanInterval=0`. If you want to disable it, please set `ScanSchedule=""`

Closes #1085

scanner/scanner.go

@@ -16,7 +16,6 @@ import (
 )
 
 type Scanner interface {
-	Run(ctx context.Context, interval time.Duration)
 	RescanAll(ctx context.Context, fullRescan bool) error
 	Status(mediaFolder string) (*StatusInfo, error)
 	Scanning() bool
@@ -72,23 +71,6 @@ func New(ds model.DataStore, cacheWarmer core.CacheWarmer, broker events.Broker)
 	return s
 }
 
-func (s *scanner) Run(ctx context.Context, interval time.Duration) {
-	ticker := time.NewTicker(interval)
-	defer ticker.Stop()
-	for {
-		err := s.RescanAll(ctx, false)
-		if err != nil {
-			log.Error(err)
-		}
-		select {
-		case <-ticker.C:
-			continue
-		case <-ctx.Done():
-			return
-		}
-	}
-}
-
 func (s *scanner) rescan(ctx context.Context, mediaFolder string, fullRescan bool) error {
 	folderScanner := s.folders[mediaFolder]
 	start := time.Now()