Refactor Cron and merge dashboard tasks (#10745)

* Refactor Cron and merge dashboard tasks

* Merge Cron and Dashboard tasks
* Make every cron task report a system notice on completion
* Refactor the creation of these tasks
* Ensure that execution counts of tasks is correct
* Allow cron tasks to be started from the cron page

* golangci-lint fixes

* Enforce that only one task with the same name can be registered

Signed-off-by: Andrew Thornton <art27@cantab.net>

* fix name check

Signed-off-by: Andrew Thornton <art27@cantab.net>

* as per @guillep2k

* as per @lafriks

Signed-off-by: Andrew Thornton <art27@cantab.net>

* Add git.CommandContext variants

Signed-off-by: Andrew Thornton <art27@cantab.net>

Co-authored-by: Lauris BH <lauris@nix.lv>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>

services/mirror/mirror.go

@@ -296,7 +296,7 @@ func Password(m *models.Mirror) string {
 }
 
 // Update checks and updates mirror repositories.
-func Update(ctx context.Context) {
+func Update(ctx context.Context) error {
 	log.Trace("Doing: Update")
 	if err := models.MirrorsIterate(func(idx int, bean interface{}) error {
 		m := bean.(*models.Mirror)
@@ -306,14 +306,17 @@ func Update(ctx context.Context) {
 		}
 		select {
 		case <-ctx.Done():
-			return fmt.Errorf("Aborted due to shutdown")
+			return fmt.Errorf("Aborted")
 		default:
 			mirrorQueue.Add(m.RepoID)
 			return nil
 		}
 	}); err != nil {
-		log.Error("Update: %v", err)
+		log.Trace("Update: %v", err)
+		return err
 	}
+	log.Trace("Finished: Update")
+	return nil
 }
 
 // SyncMirrors checks and syncs mirrors.