@W-20726574 Update template-mrt-reference-app to support testing base path support on MRT

[noahadams]

Description

• in template-mrt-reference-app, adds a middleware that looks for the environemnt variable MRT_ENV_BASE_PATH, and if it is present, rewrites request paths that start with the value to not have it
• adds relevant test cases

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

• in template-mrt-reference-app, adds a middleware that looks for the environemnt variable MRT_ENV_BASE_PATH, and if it is present, rewrites request paths that start with the value to not have it
• adds relevant test cases, and updates ssr.test.js to set headers required by the logging middleware

How to Test-Drive This PR

• checkout branch, and with Node.js v22.x installed and active, from checkout root run
• npm ci
• cd packages/template-mrt-reference-app
• npm run test

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)

[cc-prodsec]

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[vcua-mobify]

The npm 11 CI jobs are failing so it looks like you might need to do a package-lock update. But that doesn't seem related to the actual changes in this PR and this PR is going into a feature branch not develop so +1.

We'll want to ensure the npm 11 CI passes once we're ready to merge into develop.