Feature: Protected audience analysis in PSAT

[amovar18]

Description

This PR aims to give service worker the capability to run analysis of the protected audience events that run on a site.

Relevant Technical Choices

Testing Instructions

Additional Information:

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).