Add Rubocop rule or Danger check to ensure column to be renamed is ignored

This is a follow-up from Retrospective of https://gitlab.com/gitlab-com/... (#388864 - closed).

In order to prevent incidents like gitlab-com/gl-infra/production#8264 (closed) we should try to detect if the column to be renamed is ignore on the AR model backed by the respective table.

This could be Rubocop rule, or a Danger check that leaves a comment when cleanup_concurrent_column_rename is used.

The database dictionary can help with lining the database table to the model.