Add and apply Style/InvertibleUnlessCondition rule

This rule was added in rubocop 1.44.0. It's useful to avoid accidental
`unless !condition` clauses.

Note we aren't replacing `unless zero?` with `if nonzero?` because we
never use `nonzero?`; using it sounds like `if !zero?`.

Replacing `unless any?` with `if none?` is only consistent if we also replace
`unless present?` with `if blank?`, so we're also adding this case. For
consistency, we're also replacing `unless blank?` with `if present?`.

We're also simplifying code dealing with `> 0` conditions in order to
make the code (hopefully) easier to understand.

Also for consistency, we're enabling the `Style/InverseMethods` rule,
which follows a similar idea.

lib/census_api.rb

@@ -21,7 +21,7 @@ class CensusApi
     def date_of_birth
       str = data[:datos_habitante][:item][:fecha_nacimiento_string]
       day, month, year = str.match(/(\d\d?)\D(\d\d?)\D(\d\d\d?\d?)/)[1..3]
-      return nil unless day.present? && month.present? && year.present?
+      return nil if day.blank? || month.blank? || year.blank?
 
       Time.zone.local(year.to_i, month.to_i, day.to_i).to_date
     end