Replaces MongoDB support with PostgreSQL (#151)

- All schemas have been rewritten to a relational model
- All services have been rewritten to accommodate the new data model
- Adds idempotency keys to core endpoints allowing you to retry requests with no additional side effects
- Adds staged jobs to avoid putting jobs in the queue when transactions abort
- Adds atomic transactions to all methods with access to the data layer

Co-authored-by: Oliver Windall Juhl <oliver@mrbltech.com>

packages/medusa-plugin-add-ons/src/services/add-on.js

@@ -39,16 +39,7 @@ class AddOnService extends BaseService {
    * @return {string} the validated id
    */
   validateId_(rawId) {
-    const schema = Validator.objectId()
-    const { value, error } = schema.validate(rawId.toString())
-    if (error) {
-      throw new MedusaError(
-        MedusaError.Types.INVALID_ARGUMENT,
-        "The addOnId could not be casted to an ObjectId"
-      )
-    }
-
-    return value
+    return rawId
   }
 
   /**
@@ -187,7 +178,7 @@ class AddOnService extends BaseService {
     })
 
     // Return the price if we found a suitable match
-    if (price) {
+    if (price !== undefined) {
       return price
     }