Investigate/implement feature flagging/rollout solution

[ygrishajev]

Recently we faced a need to:

• be flexible in toggling some features in the console
• control rollout of some features (e.g. only for testers, some certain users)

There are some ready to use solutions. This task is to investigate potential options, pick one and create and set it up.

Should be followed by another task to integrate it into our apps (console api/web) once done.

[ygrishajev]

One potential tool we could use for this is https://www.getunleash.io/. I have been using it in the past and can give a positive feedback about it. The functionality of it is pretty rich. Some of it which I used:

1. possibility to create user segments to roll out features to
2. rolling feature releases
3. feature toggles
4. A/B testing
5. can be deployed on premises. there're helm charts which should make kick off easy https://github.com/Unleash/helm-charts