Refactor: Extension UI and Service Worker.

[amovar18]

Description

This PR aims to improve the developer experience by breaking the code into small pieces and increasing the readability of the code.

Relevant Technical Choices

• For cookies landing page components are exported from the design-system assembled in the extension and then passed down the landing page as children.
• The service worker now reuses most of the code to parse headers.
• The Service worker uses constant for message passing types.

Testing Instructions

Screenshot/Screencast

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Checklist

• I have thoroughly tested this code to the best of my abilities.
• I have reviewed the code myself before requesting a review.
• This code is covered by unit tests to verify that it works as intended.
• The QA of this PR is done by a member of the QA team (to be checked by QA).

[ayushnirwal]

@amovar18 please resolve conflicts.