Refactor: Removes unleash from Redux store

[tuliomir]

The next version of Redux throws an error by default whenever there are non-serializable objects in its Store ( more about this on this article ). This PR is one in a series of PRs that aim to refactor all of those instances before the upgrade.

The unleash Redux property is currently initialized at the start of the application and used as a monitoring tool for dynamic feature activation. The proposed singleton solution is similar to the one on #580 , which was recently merged.

Acceptance Criteria

• Create an unleash singleton javascript module, apart from the Redux store
• Refactor all the calls from this store property to use the singleton directly
• Remove unused code after this change

Security Checklist

• Make sure you do not include new dependencies in the project unless strictly necessary and do not include dev-dependencies as production ones. More dependencies increase the possibility of one of them being hijacked and affecting us.