feat: add job hook support

Fixes #394

internal/repository/jobHooks.go

@@ -0,0 +1,34 @@
+// Copyright (C) NHR@FAU, University Erlangen-Nuremberg.
+// All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+package repository
+
+type JobHook interface {
+	jobStartCallback()
+	jobStopCallback()
+}
+
+var hooks []JobHook
+
+func RegisterJobJook(hook JobHook) {
+	if hook != nil {
+		hooks = append(hooks, hook)
+	}
+}
+
+func CallJobStartHooks() {
+	for _, hook := range hooks {
+		if hook != nil {
+			hook.jobStartCallback()
+		}
+	}
+}
+
+func CallJobStopHooks() {
+	for _, hook := range hooks {
+		if hook != nil {
+			hook.jobStopCallback()
+		}
+	}
+}