Fix will_paginate crash when Meilisearch disabled

Using Meilisearch::Rails.active? as an alternative to checking that the
objects being replaced are actually NullObject.

For an alternative solution see meilisearch#383

The advantage of this approach is that NullObject remains opaque and
requires no special treatment, and the logic is much easier to follow
(in my opinion).

lib/meilisearch/rails/pagination/will_paginate.rb

@@ -10,6 +10,12 @@ module Rails
     module Pagination
       class WillPaginate
         def self.create(results, total_hits, options = {})
+          unless MeiliSearch::Rails.active?
+            total_hits = 0
+            options[:page] = 1
+            options[:per_page] = 1
+          end
+
           ::WillPaginate::Collection.create(options[:page], options[:per_page], total_hits) do |pager|
             pager.replace results
           end