feat: add category registration system to admin

src/main/java/fr/titionfire/ffsaf/data/model/CompetitionGuestModel.java

@@ -61,6 +61,14 @@ public class CompetitionGuestModel implements CombModel {
     )
     List<CompetitionGuestModel> guest = new ArrayList<>();
 
+    @ManyToMany(fetch = FetchType.LAZY, cascade = CascadeType.PERSIST)
+    @JoinTable(
+            name = "categories_insc_guest",
+            joinColumns = @JoinColumn(name = "guest_id"),
+            inverseJoinColumns = @JoinColumn(name = "category_id")
+    )
+    List<CatPresetModel> categoriesInscrites = new ArrayList<>();
+
     public CompetitionGuestModel(String s) {
         this.fname = s.substring(0, s.indexOf(" "));
         this.lname = s.substring(s.indexOf(" ") + 1);