Feature: Add collapsible sidebar

[mayan-000]

Description

• This PR adds logic and UI to show a collapsible sidebar.

Relevant Technical Choices

• A new type, CollapsedSidebarItems, needs to be submitted to the provided props to allow collapsible sidebar logic to run.

Testing Instructions

• Open PSAT panel and find double arrow beside Privacy sandbox item.
• Click on the arrow, the sidebar should collapse and screen will be expanded.
• Now clicking on the double arrow should expand the sidebar.

Additional Information:

Screenshot/Screencast

https://github.com/user-attachments/assets/3e445e64-fed3-403a-be9b-38079eabb719

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Checklist

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

Fixes #

[milindmore22]

QA issue

The icon for closing the sidebar is visible for slight movement and also has a transparent background before closing, making text below the icon overlap.

Please check the video at 0:08 second

https://github.com/user-attachments/assets/23a8c1bc-7e8e-4bfe-b72d-55649a2e828a

[pavanpatil1]

• [ ] In dark mode, the icon is hard to see. can we change it to white for better visibility?

[mohdsayed]

@mayan-000 Lets use the same settings icon in both collapsed and expanded view. I think the new settings icon is better than what we have.