🚩(project) add more backend AI feature flags

The Blocknote AI feature is a bit flaky, we want
to be able to disable it if to much issues arise,
without having to do a new release.
We add a bunch of feature flags to be able to
disable the AI features if needed:
- add AI_FEATURE_BLOCKNOTE_ENABLED, to display
or not the feature powered by blocknote
- add AI_FEATURE_LEGACY_ENABLED, to display or not
the legacy AI features

env.d/development/common

@@ -64,6 +64,8 @@ USER_RECONCILIATION_FORM_URL=http://localhost:3000
 
 # AI
 AI_FEATURE_ENABLED=true
+AI_FEATURE_BLOCKNOTE_ENABLED=true
+AI_FEATURE_LEGACY_ENABLED=true
 AI_BASE_URL=https://openaiendpoint.com
 AI_API_KEY=password
 AI_MODEL=llama