Sort types in generated schema

Otherwise, added types order may depend on file load order which is not
always deterministic if the files don't depend on each other.

lib/graphiti/schema.rb

@@ -42,7 +42,7 @@ def generate
 
     def generate_types
       {}.tap do |types|
-        Graphiti::Types.map.each_pair do |name, config|
+        Graphiti::Types.map.sort.each_entry do |name, config|
           types[name] = config.slice(:kind, :description)
         end
       end

spec/schema_spec.rb

@@ -244,6 +244,10 @@ def self.name
       expect(schema[:types]).to eq(expected[:types])
     end
 
+    it "has sorted types" do
+      expect(schema[:types].to_a).to eq(expected[:types].sort)
+    end
+
     # Dynamically-created resources, e.g. remote resources
     context "when resource has missing name" do
       let(:no_name) do