Don't add classes to the top level namespace

I've been writing too much Rust. My mind is still in the mode of things
being auto-namespaced based on the file...

activerecord/lib/active_record/connection_adapters/determine_if_preparable_visitor.rb

@@ -1,18 +1,22 @@
-module DetermineIfPreparableVisitor
+module ActiveRecord
-  attr_reader :preparable
+  module ConnectionAdapters
+    module DetermineIfPreparableVisitor
+      attr_reader :preparable
 
-  def accept(*)
+      def accept(*)
-    @preparable = true
+        @preparable = true
-    super
+        super
-  end
+      end
 
-  def visit_Arel_Nodes_In(*)
+      def visit_Arel_Nodes_In(*)
-    @preparable = false
+        @preparable = false
-    super
+        super
-  end
+      end
 
-  def visit_Arel_Nodes_SqlLiteral(*)
+      def visit_Arel_Nodes_SqlLiteral(*)
-    @preparable = false
+        @preparable = false
-    super
+        super
+      end
+    end
   end
 end