Feature: Add multi-seller auction

[mohdsayed]

Description

This PR adds multi-seller auction flow when the new "Multi seller" checkbox is checked.

Relevant Technical Choices

1. Refactor code to break it down into multiple files and folder as the code for steps was growing very large.
2. Introduce new Text and Custom components to handle new requirements for the multi-seller.
3. Add all steps for component auction.

Testing Instructions

1. Open Protected Audience > Explorable Explanations tab.
2. Click on the newly added "Multi Seller" checkbox.
3. Observer the auction for publisher pub1.com and pub2.com, they should now show multi-seller auction

Additional Information:

I found out that the spacing in the auction changes when the speed changes. It requires some debugging and will be fixed in the next PR.

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).

Partially addresses #857