feat(backend): Entities toegevoegd

Entites Class, Class Join Request, Class Invitation, Assignment, Group en entities om de Dwengo-leerinhoud te modelleren, toegevoegd.

backend/src/entities/classes/class.entity.ts

@@ -0,0 +1,19 @@
+import {Collection, Entity, ManyToMany, PrimaryKey, Property} from "@mikro-orm/core";
+import { v4 } from 'uuid';
+import {Teacher} from "../users/teacher.entity";
+import {Student} from "../users/student.entity";
+
+@Entity()
+export class Class {
+    @PrimaryKey()
+    classId = v4();
+
+    @Property({type: "string"})
+    displayName!: string;
+
+    @ManyToMany(() => Teacher)
+    teachers!: Collection<Teacher>;
+
+    @ManyToMany(() => Student)
+    students!: Collection<Student>;
+}