feat: add library migration list endpoint [FC-0112] (openedx#37567)

This PR adds the `/api/modulestore_migrator/v1/library/:libraryId/migrations/courses/` endpoint, which returns all course migrations for a target library.

Author: rpenido

cms/djangoapps/modulestore_migrator/rest_api/v1/urls.py

@@ -11,5 +11,11 @@
 ROUTER = SimpleRouter()
 ROUTER.register(r'migrations', MigrationViewSet, basename='migrations')
 ROUTER.register(r'bulk_migration', BulkMigrationViewSet, basename='bulk-migration')
+ROUTER.register(
+    r'library/(?P<lib_key_str>[^/.]+)/migrations/courses',
+    LibraryCourseMigrationViewSet,
+    basename='library-migrations',
+)
+
 
 urlpatterns = ROUTER.urls

cms/djangoapps/modulestore_migrator/rest_api/v1/views.py

@@ -371,3 +371,55 @@ def cancel(self, request, *args, **kwargs):
         We disable this endpoint to avoid confusion.
         """
         raise NotImplementedError
+
+
+@apidocs.schema_for(
+    "list",
+    "List all course migrations to a library.",
+    responses={
+        201: LibraryMigrationCourseSerializer,
+        401: "The requester is not authenticated.",
+        403: "The requester does not have permission to access the library.",
+    },
+)
+class LibraryCourseMigrationViewSet(GenericViewSet, ListModelMixin):
+    """
+    Show infomation about migrations related to a destination library.
+    """
+
+    serializer_class = LibraryMigrationCourseSerializer
+    pagination_class = None
+    queryset = ModulestoreMigration.objects.all().select_related('target_collection', 'target', 'task_status')
+
+    def get_serializer_context(self):
+        """
+        Add course name list to the serializer context.
+
+        We need to display the course names in the migration view, and we get all of
+        them here to avoid futher queries.
+        """
+        context = super().get_serializer_context()
+        queryset = self.get_queryset()
+        course_keys = queryset.values_list('source__key', flat=True)
+        courses = CourseOverview.get_all_courses(course_keys=course_keys)
+        context['course_names'] = dict((str(course.id), course.display_name) for course in courses)
+        return context
+
+    def get_queryset(self):
+        """
+        Override the default queryset to filter by the library key and check permissions.
+        """
+        queryset = super().get_queryset()
+        lib_key_str = self.kwargs['lib_key_str']
+        try:
+            library_key = LibraryLocatorV2.from_string(lib_key_str)
+        except InvalidKeyError as exc:
+            raise ParseError(detail=f"Malformed library key: {lib_key_str}") from exc
+        lib_api.require_permission_for_library_key(
+            library_key,
+            self.request.user,
+            lib_api.permissions.CAN_VIEW_THIS_CONTENT_LIBRARY
+        )
+        queryset = queryset.filter(target__key=library_key, source__key__startswith='course-v1')
+
+        return queryset