chore(data-modeling): bootstrap data modeling workspace

[gribnoysup]

This patch bootstraps a new workspace package in the monorepo and does some initial wiring so that the new workspace can be accessed through UI:

• bootstrap new package with create-workspace script
• add new feature flag
• add new entrypoint in the sidebar
• setup all required workspace types in the compass-workspace plugin
• pass the plugin to the workspaces provider so that it can be rendered

I tried to structure commits in a way that should make it a bit easier to look through, most notably the first one has a decent amount of autogenerated code from the script, all the follow-up ones should be more straightforward

[Anemy]

lgtm! One question on a default we might want to unset