Spike AB testing

[elceebee]

Context

Changes proposed in this pull request

Guidance to review

Things to check

• If the code removes any existing feature flags, a data migration has also been added to delete the entry from the database
• This code does not rely on migrations in the same Pull Request
• If this code includes a migration adding or changing columns, it also backfills existing records for consistency
• If this code adds a column to the DB, decide whether it needs to be in analytics yml file or analytics blocklist
• API release notes have been updated if necessary
• If it adds a significant user-facing change, is it documented in the CHANGELOG?
• Required environment variables have been updated added to the Azure KeyVault
• Inform data insights team due to database changes
• Make sure all information from the Trello card is in here
• Rebased main
• Cleaned commit history
• Tested by running locally
• Add PR link to Trello card

[elceebee]

AB testing spike

[elceebee]

This can serve as a example for when we want to implement this gem, but not adding now as no specific use case exists.