Add OBO Registry to OBO Metadata Editor

[jamesaoverton]

This will involved a number of steps, as you see fit @jannahastings.

I want to be merging smallish changes into master and deploying them on a regular basis, but I don't want to show registry editing on https://editor.obolibrary.org until this is ready. So I think we should use a "Feature Flag". We could reuse the FLASK_ENV variable: showing the registry stuff for FLASK_ENV=development but not for FLASK_ENV=production. Or we could use our own flag.

Here are some of the steps that I think will be required:

• implement feature flag
• configure second repository
• configure second set of schemas
• handle new URL paths
• new button on index page: "Edit Registry"
• add fields to new project form
• two step project addition? OR two editors in on page
• select/detect validation profile? foundry, active, orphan, obsolete
• configure second set of autocompletes