[Storefront Preview] SCAPI cache breaker for older v2 PWA Kit (@W-15214446@)

[vmarta]

Porting the changes from #1701. Unfortunately, while the solution/concept is still the same, the implementation had to be different.

In the older V2 PWA Kit:

• The StorefrontPreview component does not have access to the commerce api clients because they're not in the same package
• The Proxy mechanism has already been used. So we need to add the cache breaker using the existing mechanism (see willSendRequest)

Types of Changes

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Documentation update
• Breaking change (could cause existing functionality to not work as expected)
• Other changes (non-breaking changes that does not fit any of the above)

Breaking changes include:

• Removing a public function or component or prop
• Adding a required argument to a function
• Changing the data type of a function parameter or return value
• Adding a new peer dependency to package.json

Changes

• (change1)

How to Test-Drive This PR

https://runtime.commercecloud.com/mobify/blitz/will/preview?path=/global/en-GB/product/25695327M?color%3DJJI15XX%26size%3D9SM%26pid%3D701644153083M

1. Note that the product price should be the regular price
2. In the Preview form, enter tester=yes as the custom qualifier
3. Click on the Preview button
4. The price is immediately updated with the discounted promo price.

Note: to verify that the environment is actually using a bundle for the older PWA Kit, you can add an item to the cart, and that should result in an OCAPI call (not SCAPI).

Checklists

General

• Changes are covered by test cases
• CHANGELOG.md updated with a short description of changes (not required for documentation updates)

Accessibility Compliance

You must check off all items in one of the follow two lists:

• There are no changes to UI

or...

• Changes were tested with a Screen Reader (iOS VoiceOver or Android Talkback) and had no issues
• Changes comply with WCAG 2.0 guidelines levels A and AA
• Changes to common UI patterns and interactions comply with WAI-ARIA best practices

Localization

• Changes include a UI text update in the Retail React App (which requires translation)