New cop to detect `where.blank?` antipattern

[fatkodima]

blank?/present? on the relation loads the whole relation to determine if there are records in them. empty?/any? does a simple "exists" like query.

# bad
users.where(active: true).present?
users.where(active: true).blank?

users.where(active: true).any?
users.where(active: true).empty?

One of these cases was responsible for 10% of the whole IO on a loaded production database. I also found 20+ other examples of this antipattern in the codebase.

Cop can be named something like Rails/WhereBlank.

[koic]

Can you propose this to the style guide first?
https://github.com/rubocop/rails-style-guide