[REFACTOR] PWA adapted to Fastify

[giulianok]

Description

PWA changes needed to work with Fastify

Motivation and Context

The React HTML PR (https://github.com/americanexpress/one-app/pull/856/files#diff-49dfc5aceb91d68c288f11674343c97ac8f103f2da9f4e73ec6f2b4009d2a841) takes care of rendering the PWA app shell. These are the needed changes to make PWA work with React HTML app shell

How Has This Been Tested?

Manual, Unit Testing, Integration Test

Types of Changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation (adding or updating documentation)
• Dependency update
• Security update

Checklist:

• My change requires a change to the documentation and I have updated the documentation accordingly.
• These changes should be applied to a maintenance branch.
• This change requires cross browser checks.
• Performance tests should be ran against the server prior to merging.
• This change impacts caching for client browsers.
• This change impacts HTTP headers.
• This change adds additional environment variable requirements for One App users.
• I have added the Apache 2.0 license header to any new files created.

What is the Impact to Developers Using One App?

[giulianok]

offline.jsx was removed since it was moved into react html (see https://github.com/americanexpress/one-app/pull/856/files#diff-49dfc5aceb91d68c288f11674343c97ac8f103f2da9f4e73ec6f2b4009d2a841)

[github-actions]

Size Change: 0 B

Total Size: 681 kB

ℹ️ View Unchanged

Filename	Size
./build/app/app.js	165 kB
./build/app/app~vendors.js	387 kB
./build/app/runtime.js	7.07 kB
./build/app/service-worker-client.js	7.26 kB
./build/app/vendors.js	114 kB

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[10xLaCroixDrinker]

Why was this middleware deleted?

[giulianok]

because it was moved into the react html plugin (see #856)