Include postcode in Vietnam address format

[jorgeatorres]

Submission Review Guidelines:

• I have followed the WooCommerce Contributing Guidelines and the WordPress Coding Standards.
• I have checked to ensure there aren't other open Pull Requests for the same update/change.
• I have reviewed my code for security best practices.
• Following the above guidelines will result in quick merges and clear and detailed feedback when appropriate.

Changes proposed in this Pull Request:

It's been reported that postcodes are, in fact, used in Vietnam.
When we originally introduced the Vietnam address format, we omitted both state and postcodes (link).

This PR adds the postcode to the address format, following the UPU's address format for Vietnam, which indicates that the postcode should go next to the province/city.

Closes #39164.

How to test the changes in this Pull Request:

Using the WooCommerce Testing Instructions Guide, include your detailed testing instructions:

1. Add a product to the cart.
2. Complete checkout for said product using Vietnam as country and any details you want. Make sure to include a postcode and address line 2.
3. Go to the admin and to the specific order created in the previous step.
4. Confirm that:
   • On trunk, neither "Billing Address" nor "Shipping Address" (if the product was shippable) include postcode or address line 2 information.
     Trying to edit the address does show that the postcode and address line 2 was in fact stored.
   • On this branch, both "Billing Address" and "Shipping Address" should include the postcode and address line 2 in the details.

Changelog entry

• Automatically create a changelog entry from the details below.

Significance

• Patch
• Minor
• Major

Type

• Fix - Fixes an existing bug
• Add - Adds functionality
• Update - Update existing functionality
• Dev - Development related task
• Tweak - A minor adjustment to the codebase
• Performance - Address performance issues
• Enhancement - Improvement to existing functionality

Message

Comment

[github-actions]

Hi @rrennick,

Apart from reviewing the code changes, please make sure to review the testing instructions as well.

You can follow this guide to find out what good testing instructions should look like:
https://github.com/woocommerce/woocommerce/wiki/Writing-high-quality-testing-instructions

[github-actions]

Test Results Summary

Commit SHA: bc1bb61

Test 🧪	Passed ✅	Failed 🚨	Broken 🚧	Skipped ⏭️	Unknown ❔	Total 📊	Duration ⏱️
API Tests	259	0	0	2	0	261	1m 8s
E2E Tests	189	0	0	19	0	208	12m 56s

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To view the full API test report, click here.
To view the full E2E test report, click here.
To view all test reports, visit the WooCommerce Test Reports Dashboard.

[rrennick]

Thanks for getting this one. Tested great. I added address 2 to the testing instructions as it was added to the display as well.