feat: define validators and use normalize-products step (#12473)

Fixes: FRMW-2965

In this PR we replace/remove the existing step to normalize a CSV file with the newly written CSV normalizer and also we validate the file contents further using a Zod schema.

I have duplicated the schema for now. But it is makes sense to re-use the schema for CSV validating and `/admin/products/batch`, then I can keep one source of truth under utils and re-export it. WDYT?

**Screenshots of some errors after validating the file strictly**

![CleanShot 2025-05-15 at 16 36 46@2x](https://github.com/user-attachments/assets/c7fa424f-b947-4898-9b94-47c48617c129)

![CleanShot 2025-05-15 at 16 36 34@2x](https://github.com/user-attachments/assets/0fefef79-148b-4eeb-8ef0-3077e8063ea8)

yarn.lock

@@ -23530,6 +23530,7 @@ __metadata:
     "@swc/jest": ^0.2.36
     form-data: ^4.0.0
     jest: ^29.7.0
+    json-2-csv: ^5.5.9
     jsonwebtoken: ^9.0.2
     pg: ^8.11.3
     typescript: ^5.6.2
@@ -25062,6 +25063,16 @@ __metadata:
   languageName: node
   linkType: hard
 
+"json-2-csv@npm:^5.5.9":
+  version: 5.5.9
+  resolution: "json-2-csv@npm:5.5.9"
+  dependencies:
+    deeks: 3.1.0
+    doc-path: 4.1.1
+  checksum: 109b7636ba3ef9b8c53580f89280568e1ecd106b6328f44636869a62eac1f9f2db7a52de0eee04832fa20d4bd9c592ad3fe1a4cf06af0eee3ee612b85f29ed75
+  languageName: node
+  linkType: hard
+
 "json-buffer@npm:3.0.1":
   version: 3.0.1
   resolution: "json-buffer@npm:3.0.1"