Add plugintypeimpl script type

Author: acdvs

docs/rules/entry-points.md

@@ -136,6 +136,7 @@ define([], function () {
   - getConfigurationPageUrl
 - workbookbuilderplugin
   - createWorkbook
+- plugintypeimpl
 
 ## Version
 

docs/rules/script-type.md

@@ -62,6 +62,7 @@ Valid tag values are found below.
 - fiConnectivityPlugin
 - fiParserPlugin
 - workbookbuilderplugin
+- plugintypeimpl
 
 ## Version
 

lib/util/scriptTypes.js

@@ -81,4 +81,7 @@ module.exports = {
   workbookbuilderplugin: {
     entryPoints: ['createWorkbook'],
   },
+  plugintypeimpl: {
+    entryPoints: [],
+  },
 };