Allow types to be specified when instantiating a typed hash

lib/vagrant/action/builtin/mixin_synced_folders.rb

@@ -270,9 +270,7 @@ module Vagrant
           # If the file doesn't exist, we probably just have a machine created
           # by a version of Vagrant that didn't cache shared folders. Report no
           # shared folders to be safe.
-          folders = Vagrant::Util::TypedHash.new()
-          folders.types = {}
-          folders
+          Vagrant::Util::TypedHash.new(types: {})
         end
       end
     end

lib/vagrant/util/typed_hash.rb

@@ -5,6 +5,11 @@ module Vagrant
       # Types available in the Hash
       attr_accessor :types
 
+      def initialize(**opts)
+        if opts[:types]
+          @types = opts[:types]
+        end
+      end
     end
   end
 end