Playground page for contributions

Would that be a good idea to add a playground page for anyone who needs to contribute and check particular component/set of components, so that contributors won't have to create that page each time by them selves or using example page with example components as a playground?

Benefits to add such a feature are:
1. Start working on the issue immediately instead of making appropriate circumstances in a file bloated with already existing useless code
2. Automatically git will ignore any changes in the playground, so you won't have to delete any code and make sure that you've wrote only clear code ( without useless comments of code and etc... )
3. Comfortable for contributors

首先调研现有的示例页面和贡献流程；该 issue 没有指定具体的文件、测试或入口点。完成这项工作需要有一个经过一致同意的 playground 页面，用于测试组件，并将贡献者的更改排除在正常代码更改之外。

由索引模型根据 Issue 内容生成。