Add ES_PRESET option to customize numbers of shards and replicas (#26483)

Co-authored-by: Eugen Rochko <eugen@zeonfederated.com>

lib/chewy/settings_extensions.rb

@@ -0,0 +1,11 @@
+# frozen_string_literal: true
+
+module Chewy
+  module SettingsExtensions
+    def enabled?
+      settings[:enabled]
+    end
+  end
+end
+
+Chewy.extend(Chewy::SettingsExtensions)