PA EE code refactoring and small fixes

[mohdsayed]

Description

• Change background to white and fix circle override
• Change circle color to visited green after visit
• Show info info to only boxes with info
• Fix arrows not taking colors.
• Use smooth() for main canvas
• Create separate functions for setting up ad auction, ssp flow, branches and ad unit code

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).

Partially addresses #857

[amovar18]

LGTM!