[React/Flask] Add Feature Flags integration to empower

[lukemun]

Adds a convenient way for our team and sales to demo the capabilities of Feature flag integrations.

[ ] Instrument feature flags to toggle a feature or two on the website. Think up a good usecase that's simple enough to demo, but realistic enough to instrument Sentry for.

provider of choice: Statsig. As of now support is still in-progress:

[EPIC] Add Statsig as a Feature Flag Provider

[ ] SDK integration (evaluation tracking)
[ ] Webhook (change tracking)