Freemium DBP: Experiment Setup

[aataraxiaa]

Task/Issue URL: https://app.asana.com/0/1206488453854252/1208052452067283/f Tech Design URL: CC:

Description: This PR:

1. Creates the experiment manager for Freemium DBP and associated tests
2. Assigns a cohort on app startup if the user is eligible
3. Includes the cohort as a condition when deciding if Freemium DBP is available

How to Review this PR:

1. Commit 1 is only cleanup pre-implementation
2. Commit 2 & 3 is where to focus
3. Commit 4 is just post-main-rebase fix

Testing Prerequisites:

1. Make sure you are an internal user
2. Disable/Signout of Privacy Pro (Settings menu -> PP -> Remove from this device)

Steps to test this PR:

1. Launch browser
2. Go to Debug menu -> Freemium -> Log All State
3. Check the Xcode console and confirm the following experiment-related state is set (you will be in control as you are not US-based), e.g

FREEMIUM DBP: freemium.dbp.experiment.enrollment-date 2024-09-17 15:38:00 +0000
FREEMIUM DBP: freemium.dbp.experiment.cohort control

Definition of Done:

• [ ] Does this PR satisfy our Definition of Done?

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Internal references:

Pull Request Review Checklist Software Engineering Expectations Technical Design Template Pull Request Documentation

[github-actions[bot]]

	Warnings
:warning:	PR has more than 500 lines of code changing. Consider splitting into smaller PRs if possible.

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