feat: Implement create project route (SCRUM-7) (!11)

Co-authored-by: Phan Huy Tran <p.tran@neusta.de>
Reviewed-on: #11
Reviewed-by: Jan Gleytenhoover <krisellp9@gmail.com>

src/main/java/de/szut/lf8_starter/project/ProjectEntity.java

@@ -37,5 +37,7 @@ public class ProjectEntity {
     @CreatedDate
     private LocalDate startDate;
 
+    private LocalDate plannedEndDate;
+
     private LocalDate endDate;
 }