feat: implement the scheduler plugin

This also performs a one-time migration of the DOKKU_SCHEDULER values the scheduler plugin properties.

Closes #4739

plugins/scheduler/subcommands.go

@@ -0,0 +1,29 @@
+package scheduler
+
+import (
+	"github.com/dokku/dokku/plugins/common"
+)
+
+// CommandReport displays a scheduler report for one or more apps
+func CommandReport(appName string, format string, infoFlag string) error {
+	if len(appName) == 0 {
+		apps, err := common.DokkuApps()
+		if err != nil {
+			return err
+		}
+		for _, appName := range apps {
+			if err := ReportSingleApp(appName, format, infoFlag); err != nil {
+				return err
+			}
+		}
+		return nil
+	}
+
+	return ReportSingleApp(appName, format, infoFlag)
+}
+
+// CommandSet set or clear a scheduler property for an app
+func CommandSet(appName string, property string, value string) error {
+	common.CommandPropertySet("scheduler", appName, property, value, DefaultProperties, GlobalProperties)
+	return nil
+}