Replace copy configuration with automatic copying via Webpack

As mentioned in #33, the current way how copying assets (fonts, images) work is by manually configuring paths for a copy task. This works a bit against the concept of Webpack, which should automatically resolve dependencies and then copy them.

I can provide these changes via a pull request, as I already updated this behavior in my projects which are using patternlab-edition-node-webpack. So it's tested in multiple production projects.

首先追踪当前为字体和图像手动配置的复制任务，并阅读 issue #33 中的相关讨论。将现有的 asset 流程与 Webpack 依赖解析进行比较，然后验证所需的支持性 asset 是否无需手动路径即可完成复制。

由索引模型根据 Issue 内容生成。