[Shipping labels] Integrate shipping service section in main Woo Shipping label creation screen

[rachelmcr]

Part of: #14143

Description

This adds the "Shipping service" section to the main screen in the Woo Shipping label creation flow. After a package is selected during label creation:

• The shipping service section is displayed.
• The purchase button is displayed (disabled) when the bottom sheet is collapsed.

How

• Adds a temporary hasPackage property to WooShippingCreateLabelsViewModel. This can be used while the package flow under development to enable the shipping service section. (Once complete, the shipping service section will be visible after a package is selected.)
• Adds WooShippingServiceView to WooShippingCreateLabelsView, visible when hasPackage is true.
• Adds the purchase button to the collapsed bottom sheet, displayed when hasPackage is true.
• Updates the shipping rate properties in WooShippingServiceViewModel to be @Published. This ensures the main screen is redrawn when the selected shipping rate changes.

Testing information

1. Make sure the feature flag revampedShippingLabelCreation is enabled.
2. Set hasPackage to true in WooShippingCreateLabelsViewModel here.
3. Build and run the app.
4. Create an order with the processing status and at least one physical product.
5. In the order details, select "Create Shipping Label."
6. Confirm the "Shipping service" section appears on the main label creation screen.
7. Confirm you can switch tabs, sort, and select the shipping rates and signature options.
8. Confirm the (disabled) purchase button appears at the bottom of the collapsed bottom sheet.
9. Open the bottom sheet and confirm the (disabled) purchase button still appears there as before.

Screenshots

Shipping service	Selecting rates	Bottom sheet

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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	pr14229-3b56d3d
	Version	20.9
	Bundle ID	com.automattic.alpha.woocommerce
	Commit	3b56d3d
	App Center Build	WooCommerce - Prototype Builds #11315

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