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/assigments/assignment.entity.ts

@@ -0,0 +1,25 @@
+import {Entity, ManyToOne, OneToMany, PrimaryKey, Property} from "@mikro-orm/core";
+import {Class} from "../classes/class.entity";
+import {LearningPath} from "../content/learning-path.entity";
+import {Group} from "./group.entity"
+
+@Entity()
+export class Assignment {
+    @ManyToOne({entity: () => Class, primary: true})
+    within!: Class;
+
+    @PrimaryKey({type: "number"})
+    id!: number;
+
+    @Property({type: "string"})
+    title!: string;
+
+    @Property({type: "longtext"})
+    description!: string;
+
+    @ManyToOne({entity: () => LearningPath})
+    task!: LearningPath;
+
+    @OneToMany({entity: () => Group})
+    groups!: Group[];
+}