Added basic worker so tests can create them

src/main/java/hhn/temp/project/AssignmentManager.java

@@ -1,12 +1,22 @@
 package hhn.temp.project;
 
 import java.util.ArrayList;
+import java.util.HashMap;
 import java.util.List;
+import java.util.Map;
 
 public class AssignmentManager {
-    List<Worker> workerList;
+    Map<Integer, Worker> workerMap;
+    int workerIdCounter;
 
     public AssignmentManager() {
-        workerList = new ArrayList<>();
+        workerMap = new HashMap<>();
+        int workerIdCounter = 1000;
+    }
+
+    public int createWorker(String name) {
+        Worker worker = new Worker(name, ++workerIdCounter);
+        workerMap.put(workerIdCounter, worker);
+        return workerIdCounter;
     }
 }