feat: remove addEventListener API

[kieran-osgood-shopify]

What changes are you making?

The current React Native API exposes checkout.addEventListener(event, callback) for close, error, and geolocationRequest.

It operates on a "global" singleton pattern, and works well for responding to things like AppState or Keyboard, but not so much on the instances of AcceleratedCheckoutButtons or the ShopifyCheckout component.

Removing it in this PR leads us towards the future state API in upstack PR's

  <CheckoutSheet
        url={checkoutUrl}
        onCancel={() => setVisible(false)}
        onFail={() => {}}
        protocol={{
          start:    chk => analytics.track('checkout_start', { id: chk.id }),
          complete: chk => {
            reset();
            setVisible(false);
          },
          error:    err => toast(err.messages[0]?.content ?? 'Checkout error'),
        }}
      />


 ShopifyCheckoutKit.present(url, sdkHandlers, { [CheckoutProtocol.start]: c => {c.checkourUrl} })

How to test

---

Before you merge

Important

• I've added tests to support my implementation
• I have read and agree with the Contribution Guidelines
• I have read and agree with the Code of Conduct
• I've updated the relevant platform README (platforms/swift/README.md and/or platforms/android/README.md)

---

Releasing a new Swift version?

• I have bumped the version in ShopifyCheckoutKit.podspec
• I have bumped the version in platforms/swift/Sources/ShopifyCheckoutKit/ShopifyCheckoutKit.swift
• I have updated platforms/swift/CHANGELOG.md
• I have updated the SwiftPM/CocoaPods version snippets in platforms/swift/README.md (major version only)

Releasing a new Android version?

• I have bumped the versionName in platforms/android/lib/build.gradle
• I have updated platforms/android/CHANGELOG.md
• I have updated the Gradle/Maven version snippets in platforms/android/README.md

Tip

See the Contributing documentation for the full release process per platform.

[kieran-osgood-shopify]

• feat: remove addEventListener API #119 : 3 dependent PRs (#125 , #134 , #170 ) 👈 (View in Graphite)
• feat(react-native): use local android/swift project references #115 : 1 other dependent PR (#116 )
• feat(protocol): add typescript interfaces #114
• main

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

[github-actions]

React Native — Coverage Report

Lines	Statements	Branches	Functions
	97.26% (249/256)	90.5% (143/158)	100% (67/67)

[kieran-osgood-shopify]

terminology to be aligned with native implementations - previously "CheckoutDelegate" or "CheckoutEventProcessor"