[Shipping labels] Add WooShippingAddressField to represent an address field

[rachelmcr]

Part of: #13781

Description

This PR does not change the current behavior, but it encapsulates the logic for an address field in the Woo Shipping flow into WooShippingAddressField. This new type holds the field's type, its value, whether it's required, the method for validating its value, and whether it has a validation error. (This requires quite a few lines of changes to support moving the logic to the new type.)

This change simplifies how the view handles these fields: we can pass each field to its corresponding AddressTextField or AddressSelection view and use the field to populate those child views.

In the view model, each field is now a WooShippingAddressField (rather than a String for the field value). The view model is now focused on defining the rules for validating each field and handling special cases where one field depends on another (e.g. name and company fields, or state and country fields).

These changes will facilitate the validation UI behavior outlined in #14943 and hopefully make it easier to understand and maintain the logic around each field.

Testing information

For now, the validation logic isn't yet used in the UI. However, you can confirm that UI works the same as before:

1. Ensure the latest production version of WooCommerce Shipping (Version 1.3.2) is installed, activated, and set up on your store.
2. Create or open an order with at least one physical product and the processing status.
3. Tap "Create Shipping Label" in order details.
4. Open the "Shipment details" bottom sheet.
5. Tap the "Ship from" origin address.
6. Tap the edit (pencil) icon on one of the origin addresses.
7. In the edit address sheet, confirm the name is marked as required unless a company is entered.
8. Confirm the company is marked as required unless a name is entered.
9. Confirm the state is marked as required when a country with states is selected (e.g. USA), and is optional for countries without states.
10. Confirm all field labels and values are displayed as expected.

Screenshots

Opening the form	Optional company	Optional name	Required state	Optional state

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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.

[dangermattic]

	2 Warnings
⚠️	This PR is larger than 300 lines of changes. Please consider splitting it into smaller PRs for easier and faster reviews.
⚠️	This PR is assigned to the milestone 21.5. This milestone is due in less than 2 days. Please make sure to get it merged by then or assign it to a milestone with a later deadline.

Generated by 🚫 Danger

[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	pr14949-f6f9c2e
	Version	21.4
	Bundle ID	com.automattic.alpha.woocommerce
	Commit	f6f9c2e
	App Center Build	WooCommerce - Prototype Builds #12651

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

[toupper]

LGTM! 🚢