Adjust default yardoc settings

* Show all APIs, not just the ones tagged as public.
* Show private methods, show protected methods.
* Hide everything tagged with @Private
* Fix yard choking on the template files
  `.tt` is the de-facto file name to be used for templates regardless.
* Hide the generator classes in yard, they aren't useful
* Fail yardoc on warnings to prevent failures in CI

.yardopts

@@ -1 +1 @@
---api public --hide-void-return --markup markdown
+--no-private --private --protected --hide-void-return --markup markdown --fail-on-warning

lib/generators/pundit/install/install_generator.rb

@@ -1,12 +1,14 @@
 # frozen_string_literal: true
 
 module Pundit
+  # @private
   module Generators
+    # @private
     class InstallGenerator < ::Rails::Generators::Base
       source_root File.expand_path("templates", __dir__)
 
       def copy_application_policy
-        template "application_policy.rb", "app/policies/application_policy.rb"
+        template "application_policy.rb.tt", "app/policies/application_policy.rb"
       end
     end
   end

lib/generators/pundit/policy/policy_generator.rb

@@ -1,12 +1,14 @@
 # frozen_string_literal: true
 
 module Pundit
+  # @private
   module Generators
+    # @private
     class PolicyGenerator < ::Rails::Generators::NamedBase
       source_root File.expand_path("templates", __dir__)
 
       def create_policy
-        template "policy.rb", File.join("app/policies", class_path, "#{file_name}_policy.rb")
+        template "policy.rb.tt", File.join("app/policies", class_path, "#{file_name}_policy.rb")
       end
 
       hook_for :test_framework

lib/generators/rspec/policy_generator.rb

@@ -1,12 +1,14 @@
 # frozen_string_literal: true
 
+# @private
 module Rspec
+  # @private
   module Generators
     class PolicyGenerator < ::Rails::Generators::NamedBase
       source_root File.expand_path("templates", __dir__)
 
       def create_policy_spec
-        template "policy_spec.rb", File.join("spec/policies", class_path, "#{file_name}_policy_spec.rb")
+        template "policy_spec.rb.tt", File.join("spec/policies", class_path, "#{file_name}_policy_spec.rb")
       end
     end
   end

lib/generators/test_unit/policy_generator.rb

@@ -1,12 +1,14 @@
 # frozen_string_literal: true
 
+# @private
 module TestUnit
+  # @private
   module Generators
     class PolicyGenerator < ::Rails::Generators::NamedBase
       source_root File.expand_path("templates", __dir__)
 
       def create_policy_test
-        template "policy_test.rb", File.join("test/policies", class_path, "#{file_name}_policy_test.rb")
+        template "policy_test.rb.tt", File.join("test/policies", class_path, "#{file_name}_policy_test.rb")
       end
     end
   end