Feature flags (#543)

* Re-organize a bit controllers

* Added the featureflagcontroller

* Implement feature flags in the front-end

* Clean env files

* Clean console.log messages

* Fix feature flag test

client/.env.example

@@ -1,13 +1,9 @@
 NUXT_LOG_LEVEL=
 NUXT_PUBLIC_APP_URL=
 NUXT_PUBLIC_API_BASE=
-NUXT_PUBLIC_AI_FEATURES_ENABLED=
 NUXT_PUBLIC_AMPLITUDE_CODE=
 NUXT_PUBLIC_CRISP_WEBSITE_ID=
-NUXT_PUBLIC_CUSTOM_DOMAINS_ENABLED=
 NUXT_PUBLIC_ENV=
 NUXT_PUBLIC_GOOGLE_ANALYTICS_CODE=
 NUXT_PUBLIC_H_CAPTCHA_SITE_KEY=
-NUXT_PUBLIC_PAID_PLANS_ENABLED=
-NUXT_PUBLIC_S3_ENABLED=
 NUXT_API_SECRET=secret