Shipping Label: Edit and remove HAZMAT category

[itsmeichigo]

Closes: #15316
Also closes #15317
Also closes #15311

Description

This PR wraps up the HAZMAT functionality of the new shipping label flow:

• Updated the HAZMAT detail view to display the currently selected category.
• Added a button to save selection when disabling HAZMAT after selecting a category.

Steps to reproduce

1. Log in to a test store with Woo Shipping plugin set up.
2. Select a completed order with at least one physical product.
3. Select Create shipping label > tap the HAZMAT row.
4. Switch on HAZMAT then select any category.
5. Tap the HAZMAT row again then confirm that the selected category is displayed correctly.
6. Tap the pencil button and select a different category. Confirm that the HAZMAT detail view is dismissed and the new category is displayed on the creation form.
7. Tap the HAZMAT row again then turn off HAZMAT using the toggle.
8. Confirm that the Save button shows up at the bottom. Tap the button.
9. Confirm that the HAZMAT detail view is dismissed and the creation form shows that no HAZMAT category is set. Confirm that the correct notice is displayed in this case.

Testing information

Tested on simulator iPhone 16 Pro iOS 18.2 and confirm the above test cases.

Screenshots

Simulator.Screen.Recording.-.iPhone.16.Pro.-.2025-03-24.at.15.04.16.mp4

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

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 all devices (phone/tablet) and no regressions are added.

[wpmobilebot]

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

	App Name	WooCommerce iOS
	Build Number	pr15405-f1ddaf0
	Version	22.0
	Bundle ID	com.automattic.alpha.woocommerce
	Commit	f1ddaf0
	App Center Build	WooCommerce - Prototype Builds #13389

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[selanthiraiyan]

Looks great. 🚀