[Shipping labels] Print shipping label when print button is tapped

[rachelmcr]

Closes: #14538
Closes: #13685

Description

When the print button is tapped in the Woo Shipping label flow, we now fetch the label data from remote and present the print dialog. This doesn't change the behavior in the order details screen, which will be updated in a separate milestone.

How

• Adds WooShippingPostPurchaseViewModel.printLabel(), which calls the action to fetch the label data and then presents it in the Air Print dialog.
• Adds a new button style HighlightLoadingButtonStyle, which shows the HighlightButtonStyle with a loading indicator when the button is loading.
• Updates WooShippingPostPurchaseView to use the new button style and printLabel() method when the button is tapped.

Testing information

Prerequisites: The WooCommerce Shipping extension is active on your store, and you have at least one order with a purchased shipping label.

1. Enable the revampedShippingLabelCreation feature flag.
2. Build and run the app.
3. Go the Orders tab.
4. Select an order with a purchased shipping label.
5. Tap "View purchased shipping label."
6. Select a paper size and tap the Print Shipping Label button.
7. Confirm the button is disabled and shows a loading indicator while the label data is being fetched.
8. After the label data loads, confirm the Air Print dialog appears with the shipping label.

Note: The available paper sizes in the Air Print dialog will depend on your selected printer.

Screenshots

Simulator.Screen.Recording.-.iPhone.16.Pro.-.2024-11-27.at.16.58.01.mp4

---

• 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	pr14545-c0cc5b3
	Version	21.2
	Bundle ID	com.automattic.alpha.woocommerce
	Commit	c0cc5b3
	App Center Build	WooCommerce - Prototype Builds #11801

Automatticians: You can use our internal self-serve MC tool to give yourself access to App Center if needed.