✨(api) add CRUD for mailbox manager MailDomain models

Add create,list,retrieve and delete actions for MailDomain model.

src/backend/mailbox_manager/urls.py

@@ -0,0 +1,41 @@
+"""API URL Configuration"""
+
+from django.urls import include, path, re_path
+
+from rest_framework.routers import DefaultRouter
+
+from mailbox_manager.api import viewsets
+
+maildomain_router = DefaultRouter()
+maildomain_router.register(
+    "mail-domains", viewsets.MailDomainViewSet, basename="mail-domains"
+)
+
+# - Routes nested under a mail domain
+maildomain_related_router = DefaultRouter()
+maildomain_related_router.register(
+    "accesses",
+    viewsets.MailDomainAccessViewSet,
+    basename="accesses",
+)
+maildomain_related_router.register(
+    "mailboxes",
+    viewsets.MailBoxViewSet,
+    basename="mailboxes",
+)
+
+
+urlpatterns = [
+    path(
+        "",
+        include(
+            [
+                *maildomain_router.urls,
+                re_path(
+                    r"^mail-domains/(?P<domain_id>[0-9a-z-]*)/",
+                    include(maildomain_related_router.urls),
+                ),
+            ]
+        ),
+    ),
+]