Cop enforcing using map for search instead of arrays

[dmitrytrager]

If we need to look for value, map is usually better option than array.

I often see something like this:

values = <collect into array>
collection.each do |item|
  values.select { |v| v['attr'] = item.some_method }
end

It could be more performant to have this instead:

values = <collect into map>
collection.each do |item|
  values[item.some_method]
end

Maybe a new cop could help here.
Since map is not always the right choice, some enforcing style options could be useful too.