Add spacing separator style to Address Element

[tillh-stripe]

Summary

Motivation

Testing

Changelog

[github-actions]

🚨 New dead code detected in this PR:

AddressSectionElement.swift:127 warning: Unused property 'addressSection'
AddressSectionElement.swift:214 warning: Unused parameter 'title'

Please remove the dead code before merging.

If this is intentional, you can bypass this check by adding the label skip dead code check to this PR.

ℹ️ If this comment appears to be left in error, double check that the flagged code is actually used and/or make sure your branch is up-to-date with master.

[find-dead-code]

[github-actions]

⚠️ Public API changes detected:

StripePaymentSheet

- public init(defaultValues: StripePaymentSheet.AddressViewController.Configuration.DefaultAddressDetails = .init(), additionalFields: StripePaymentSheet.AddressViewController.Configuration.AdditionalFields = .init(), allowedCountries: [Swift.String] = [], appearance: StripePaymentSheet.PaymentSheet.Appearance = PaymentSheet.Appearance.default, buttonTitle: Swift.String? = nil, title: Swift.String? = nil)
+ public init(defaultValues: StripePaymentSheet.AddressViewController.Configuration.DefaultAddressDetails = .init(), additionalFields: StripePaymentSheet.AddressViewController.Configuration.AdditionalFields = .init(), allowedCountries: [Swift.String] = [], appearance: StripePaymentSheet.PaymentSheet.Appearance = PaymentSheet.Appearance.default, separatorStyle: StripePaymentSheet.AddressViewController.SeparatorDisplayStyle = .divider, buttonTitle: Swift.String? = nil, title: Swift.String? = nil)
+ public typealias SeparatorDisplayStyle = StripeUICore.SeparatorDisplayStyle

StripeUICore

+ case divider
+ case spacing(CoreFoundation.CGFloat)

If you are adding a new public API consider the following:

• Do these APIs need to be public or can they be protected with @_spi(STP)?
• If these APIs need to be public, assess whether they require an API review.

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• Does this require a breaking version change?
• Do these changes require API review?

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