Refactor: split memory API into gateway and service layers (#13111)

### What problem does this PR solve?

Decouple the memory API into a gateway layer (for routing/param parse)
and a service layer (for business logic).

### Type of change

- [x] Refactoring

common/exceptions.py

@@ -16,3 +16,13 @@
 class TaskCanceledException(Exception):
     def __init__(self, msg):
         self.msg = msg
+
+
+class ArgumentException(Exception):
+    def __init__(self, msg):
+        self.msg = msg
+
+
+class NotFoundException(Exception):
+    def __init__(self, msg):
+        self.msg = msg