Draft: POC for protocells unsupported features

What does this MR do and why?

Related to gitlab-com/gl-infra&1709

An example of how we could use a list of unsupported controllers to show a message for features that are not supported in protocells.

We can get a list of all controllers by running the following in the Rails console:

Rails.application.routes.routes.map { |route| route.defaults[:controller]  }.compact.uniq.sort

We would then have to go through that list and add the controllers that will not work in protocells to config/organization_protocells_unsupported_controllers.yml

Screenshots or screen recordings

How to set up and validate locally

1. Check out this branch and restart GDK
2. Go to /rails/features and enable ui_for_organizations feature flag
3. Go to /dashboard/snippets

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