feat: add flipper for feature flags

[elasticspoon]

I've added the flipper gem (https://www.flippercloud.io/docs) for managing feature toggles. I also put in flipper-ui for a nice web based interface for flipper that you can access at /flipper.

To do so, you need to have environment variables set for FLIPPER_USERNAME and FLIPPER_PASSWORD. You can set these in your .env file.

The defaults in QA will be username: admin and password: password. Production credentials will differ.

[compwron]

Nice. Do keep in mind that we have an existing handrolled feature flag system that you should unify at some point

[compwron]

https://github.com/rubyforgood/casa/blob/main/app/services/feature_flag_service.rb

[elasticspoon]

I think I would also roll the fund request logic in, since there is not user facing way to toggle them.

casa/lib/tasks/deployment/20220409174149_enable_feature_flag_prince_george_fund_request.rake

Line 9 in 259dd5b

casa_org&.update!(show_fund_request: true)