[Refunds] Fix taxes handling

[hichamboushaba]

Closes: WOOMOB-395

Description

This PR builds on top of the previous PR to fix the issue of tax refunding, as for now, we weren't handling it correctly.
This PR updates the logic of the refunding to handle splitting the taxes refund according to each item taxes.

Important: There is a discrepancy between the taxes array that each order line returns, and the total_tax, the total_tax is rounded, while the values in the array are raw. Initially, I wanted to avoid making any calculations on client side, and drop the amount argument from the API call, but I noticed an issue where the refunds could have less amount that the total order amount, so for now, we'll still send the amount, and its value will still use the total_tax for calculation (this matches iOS behavior too).
This issue will become problematic when we try to add support for partial refunds, I asked about it here p1747301522966739-slack-C07JJG089M0, and depending on the response, I'll document the next steps.

Steps to reproduce

1. Enable tax calculation on your store.
2. Add multiple tax rates (make sure to assign different priorities so that they all get used for calculation).
3. Create an order.
4. Go to the app and refund the order.

Testing information

• Confirm refunding works as expected.
• Check wp-admin and confirm taxes were correctly refunded (as shown in the screenshots below)

The tests that have been performed

^

Images/gif

Before	After

• I have considered if this change warrants release notes and have added them to RELEASE-NOTES.txt if necessary. Use the "[Internal]" label for non-user-facing changes.

Reviewer (or Author, in the case of optional code reviews):

Please make sure these conditions are met before approving the PR, or request changes if the PR needs improvement:

• The PR is small and has a clear, single focus, or a valid explanation is provided in the description. If needed, please request to split it into smaller PRs.
• Ensure Adequate Unit Test Coverage: The changes are reasonably covered by unit tests or an explanation is provided in the PR description.
• Manual Testing: The author listed all the tests they ran, including smoke tests when needed (e.g., for refactorings). The reviewer confirmed that the PR works as expected on big (tablet) and small (phone) in case of UI changes, and no regressions are added.

[wpmobilebot]

📲 You can test the changes from this Pull Request in WooCommerce-Wear Android by scanning the QR code below to install the corresponding build.

	App Name	WooCommerce-Wear Android
	Platform	⌚️ Wear OS
	Flavor	Jalapeno
	Build Type	Debug
	Commit	9ba4f9d
	Direct Download	woocommerce-wear-prototype-build-pr14064-9ba4f9d.apk

[wpmobilebot]

📲 You can test the changes from this Pull Request in WooCommerce Android by scanning the QR code below to install the corresponding build.

	App Name	WooCommerce Android
	Platform	📱 Mobile
	Flavor	Jalapeno
	Build Type	Debug
	Commit	9ba4f9d
	Direct Download	woocommerce-prototype-build-pr14064-9ba4f9d.apk

[hichamboushaba]

This refactoring is not really needed for this PR, but it will be useful for a future refactoring of the IssueRefundViewModel.

[JorgeMucientes]

Nicely done @hichamboushaba the changes look good and work as described.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 73.62637% with 24 lines in your changes missing coverage. Please review.

Project coverage is 37.71%. Comparing base (742e877) to head (9ba4f9d).
Report is 11 commits behind head on trunk.

Files with missing lines	Patch %	Lines
...otlin/com/woocommerce/android/model/OrderMapper.kt	36.36%	0 Missing and 7 partials ⚠️
...org/wordpress/android/fluxc/store/WCRefundStore.kt	0.00%	7 Missing ⚠️
...rce/android/ui/payments/refunds/RefundsUiModels.kt	87.50%	5 Missing ⚠️
...main/kotlin/com/woocommerce/android/model/Order.kt	83.33%	2 Missing ⚠️
.../network/rest/wpcom/wc/refunds/RefundRestClient.kt	0.00%	2 Missing ⚠️
...ndroid/ui/payments/refunds/IssueRefundViewModel.kt	92.85%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##              trunk   #14064      +/-   ##
============================================
+ Coverage     37.68%   37.71%   +0.03%     
- Complexity     8885     8896      +11     
============================================
  Files          1951     1951              
  Lines        108870   108899      +29     
  Branches      14232    14239       +7     
============================================
+ Hits          41031    41076      +45     
+ Misses        64094    64072      -22     
- Partials       3745     3751       +6     

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