Add exceptions for metadata modules (#6070)

Class exception for each metadata module + handler to map on graphql
error

TODO left :
- find a way to call handler on auto-resolvers nestjs query (probably
interceptors)
- discuss what should be done for pre-hooks errors
- discuss what should be done for Unauthorized exception

packages/twenty-server/src/utils/custom-exception.ts

@@ -0,0 +1,8 @@
+export class CustomException extends Error {
+  code: string;
+
+  constructor(message: string, code: string) {
+    super(message);
+    this.code = code;
+  }
+}