feat: Add compilerFile for options

[vincenting]

For some reasons, we alway get a error when building in production mode: compiler.parseComponent is not a function.

After we tried to debug it, we found some loaders call vue-loader with stringified args, which resulting in losing all functions we declared in our config. (VueTemplateCompiler)

Here is another similar issue #1454

The easiest way to fix it is using a string param to pass the configuration of compiler. So, use a compilerFile: string will be a choose for this case.

{
  compilerFile: 'absPathToCompilerFile',
} 

[vincenting]

https://cli.vuejs.org/config/#parallel
https://github.com/webpack-contrib/terser-webpack-plugin#parallel

In production mode (vue-cli-service), parallel is enabled by default, which as a result leading to this issue. We are now disable parallel to avoid this error in production.

vue-loader is now using loader-utils#getOptions to parse params. Which means all the data structure supported by JSON is suggested as options. VueTemplateCompiler is a kind of data structure with Function, which will leave some risks in some certain conditions.

[viruscamp]

1. It's better to use the same option name.
   compiler: String | VueTemplateCompiler
2. Other loader-options that cannot be stringified , should be treat the same way. Just like:

{
  compiler:  String | VueTemplateCompiler
  compilerOptions: {
    modules: Array<string | ModuleOptions>,
    directives: { [key: string]: String | Function }
  }
}