Add support for feature flags

[dsebastien]

Goal: control rollout of, and access to certain features (e.g., beta, premium, whatever).

We'll use Laravel Pennant: https://laravel.com/docs/11.x/pennant

• Add and configure Laravel Pennant
• Publish the Pennant vendor configs
• Create a Features enum on the BE with feature names (to have type safety on the back-end)
• Add a "beta" feature
• Add a /features API endpoint to list features accessible to the current user
• Create a Features "enum" on the FE (same logic)
• Add support for the /features API endpoint on KnowiiApiClient
• Use it
• Add documentation

References:

• https://laravel.com/docs/11.x/pennant
• https://www.youtube.com/watch?v=EjLAaeHSPWY

[dsebastien]

Careful that features are resolved ONCE, stored in the database, and not changed afterwards

[dsebastien]

Use Feature::define('new-feature', Lottery::odds(1,10)); to enable a feature randomly for 10% of the users.

[dsebastien]

Use ->middleware(EnsureFeaturesAreActive::using('new-feature')); to ensure users have access to specific features

[dsebastien]

Make sure to configure feature discover so that Feature:all(); always gives the full list of features: https://laravel.com/docs/11.x/pennant#retrieving-multiple-features