cask/artifact: fix up some definitions

And expand the list of artifacts that target: works with.

Library/Homebrew/cask/artifact/abstract_artifact.rb

@@ -82,6 +82,7 @@ module Cask
             Service,
             InputMethod,
             InternetPlugin,
+            KeyboardLayout,
             AudioUnitPlugin,
             VstPlugin,
             Vst3Plugin,

Library/Homebrew/cask/artifact/keyboard_layout.rb

@@ -11,11 +11,6 @@ module Cask
     class KeyboardLayout < Moved
       extend T::Sig
 
-      sig { returns(String) }
-      def self.english_name
-        "Keyboard Layout"
-      end
-
       def install_phase(**options)
         super(**options)
         delete_keyboard_layout_cache(**options)

Library/Homebrew/cask/artifact/vst3_plugin.rb

@@ -9,6 +9,12 @@ module Cask
     #
     # @api private
     class Vst3Plugin < Moved
+      extend T::Sig
+
+      sig { returns(String) }
+      def self.english_name
+        "VST3 Plugin"
+      end
     end
   end
 end

Library/Homebrew/cask/artifact/vst_plugin.rb

@@ -9,6 +9,12 @@ module Cask
     #
     # @api private
     class VstPlugin < Moved
+      extend T::Sig
+
+      sig { returns(String) }
+      def self.english_name
+        "VST Plugin"
+      end
     end
   end
 end

docs/Cask-Cookbook.md

@@ -267,7 +267,7 @@ artifact "sapmachine-jdk-#{version}.jdk", target: "/Library/Java/JavaVirtualMach
 
 #### *target* Works on Most Artifact Types
 
-The `target:` key works similarly for most cask artifacts, such as `app`, `binary`, `colorpicker`, `dictionary`, `font`, `input_method`, `prefpane`, `qlplugin`, `mdimporter`, `service`, `suite`, and `artifact`.
+The `target:` key works similarly for most cask artifacts, such as `app`, `binary`, `colorpicker`, `dictionary`, `font`, `input_method`, `internet_plugin`, `keyboard_layout`, `prefpane`, `qlplugin`, `mdimporter`, `screen_saver`, `service`, `suite`, `audio_unit_plugin`, `vst_plugin`, `vst3_plugin`, and `artifact`.
 
 #### *target* Should Only Be Used in Select Cases