feat: Provision to set Default Item Manufacturer

- Is Default checkbox added in Item Manufacturer
- Default Item Manufacturer and Part No fields added to Item Master
- Manufacturer Part No field editable in all child tables with validation
- Manufacturer and Part No auto fetched via get_item_details in child table
diff --git a/erpnext/stock/get_item_details.py b/erpnext/stock/get_item_details.py
index b1bfc90..61429cc 100644
--- a/erpnext/stock/get_item_details.py
+++ b/erpnext/stock/get_item_details.py
@@ -341,6 +341,9 @@
 		else:
 			out["manufacturer_part_no"] = None
 			out["manufacturer"] = None
+	else:
+		out["manufacturer"], out["manufacturer_part_no"] = frappe.get_value("Item", item.name,
+			["default_item_manufacturer", "default_manufacturer_part_no"] )
 
 	child_doctype = args.doctype + ' Item'
 	meta = frappe.get_meta(child_doctype)