Support multi-page app by marking html-webpack-plugin entries as lazy

[haoqunjiang]

Currently, this plugin only deals with dynamic imports, but in real life, a common cause of slow compilation is huge multi-page apps (an example app: https://github.com/GodStream/multi-vue-cli3.0-bug).
By adding html-webpack-plguin entries to the lazyModules list, there will be great improvement to those apps. And this feature seems quite in line with this plugin's goal.

[JounQin]

@liximomo

It starts with error after upgrading.

ERROR in   Error: webpack-internal:///./node_modules/lazy-compile-webpack-plugin/lib/loaders/api.js:22
  var originTitle = document.title;
                    ^
  ReferenceError: document is not defined
  
  - api.js:22 eval
    [.]/[lazy-compile-webpack-plugin]/lib/loaders/api.js:22:19
  
  - index.pug:108 Object../node_modules/lazy-compile-webpack-plugin/lib/loaders/api.js
    /Users/JounQin/Workspaces/GitHub/pkgr/packages/webpack/index.pug:108:1
  
  - index.pug:21 __webpack_require__
    /Users/JounQin/Workspaces/GitHub/pkgr/packages/webpack/index.pug:21:30
  
  - index.pug:3 eval
    [.]/[html-webpack-plugin]/lib/loader.js!./packages/webpack/index.pug:3:11
  
  - index.pug:97 Object../node_modules/html-webpack-plugin/lib/loader.js!./packages/webpack/index.pug
    /Users/JounQin/Workspaces/GitHub/pkgr/packages/webpack/index.pug:97:1
  
  - index.pug:21 __webpack_require__
    /Users/JounQin/Workspaces/GitHub/pkgr/packages/webpack/index.pug:21:30
  
  - index.pug:85 
    /Users/JounQin/Workspaces/GitHub/pkgr/packages/webpack/index.pug:85:18
  
  - index.pug:88 
    /Users/JounQin/Workspaces/GitHub/pkgr/packages/webpack/index.pug:88:10
  
  - index.js:247 HtmlWebpackPlugin.evaluateCompilationResult
    [pkgr]/[html-webpack-plugin]/index.js:247:28

[liximomo]

@JounQin Please go to #5