Fixes https://github.com/twentyhq/core-team-issues/issues/1382
Current issue : all step output schemas are computed and stored on
backend side. Which means that, when the database schema is updated -
like a field creation - steps needs to be deleted an recreated. Which is
invisible to users.
Solution : schema generation is moved on frontend side
1. Coming on the page the first time, the schema is populated for all
steps except a few ones that are handled differently (Code, Webhook,
http node, Agent)
2. A separated state allow to determine if a step needs a recomputation.
3. The user only needs a refresh to see the whole schema re-computed
Follow-up:
- check if remaining backend steps could be moved to runtime
computation. But Code will still require storage.
- Clean backend service that is not used anymore
