Fix remaining Swift 6 concurrency issues

[kieran-osgood-shopify]

Stack Context

This stack incrementally prepares the Swift SDK and sample apps for Swift 6, with the final PR enabling Swift 6 language mode.

What?

Adds the last compatibility fixes needed immediately before flipping the language mode:

• marks remaining shared state / mock types safe for Swift 6 checking
• keeps the Checkout Kit configuration API usable from existing call sites
• updates SwiftUI and web view tests for main-actor-isolated APIs
• removes obsolete cache invalidation test setup from the renamed checkout web view flow

Why?

Keeping these fixes in a separate PR keeps the final language-mode PR focused on the actual compiler setting changes. This preserves the incremental stack so each step can be reviewed independently before kieran-osgood/05-13-featswift6languagemode turns Swift 6 on.

How to test

shadowenv exec --dir /Users/ko/src/github.com/Shopify/checkout-kit -- /opt/dev/bin/dev swift test

[kieran-osgood-shopify]

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
Learn more

• Enable swift 6 language mode #92
• Fix remaining Swift 6 concurrency issues #273 👈 (View in Graphite)
• Fix Swift 6 sample concurrency issues #99
• Apply SwiftFormat cleanup for Swift 6 stack #98 : 1 other dependent PR (#97 )
• Fix Swift 6 test target isolation #91
• Align PassKit protocol abstractions with Swift 6 #90
• Isolate wallet controllers to the main actor #89
• Make Storefront cache and GraphQL values Sendable #88
• Make generated JSON coding key Sendable #87
• Make logger shared state concurrency-safe #86
• Make CheckoutKit configuration configure-only #85
• Mark CheckoutKit UI as main actor isolated #84
• main

This stack of pull requests is managed by Graphite. Learn more about stacking.

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React Native — Coverage Report

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