Closes: #9840

Description

This PR increases the app's resilience when the app receives a String instead of an expected value type for the stockQuantity on Product or ProductVariation. (This is a known decoding error that users have experienced.)

Core sends the stock quantity as an Int or null, and we already convert that to an optional Decimal to handle plugins that allow decimal quantities. This PR adds failsafe decoding from String to Decimal, too.

Testing instructions

We don't know the exact plugins that can cause this behavior, but you can test using a tool like Charles Proxy or Proxyman to intercept and modify the response:

1. Set a breakpoint in your tool of choice for requests to the /wc/v3/products endpoint.
2. Build and run the app.
3. Open the Products tab.
4. Modify the response so a product's stock_quantity field returns a string representing a number or null value (e.g. "stock_quantity": "1" or "stock_quantity": "").
5. Execute the response and confirm the app loads the product list.

You can repeat the same steps with the variations list for a variable product, modifying the same fields in the response for a variation.

• I have considered if this change warrants user-facing release notes and have added them to RELEASE-NOTES.txt if necessary.