[feature] Plugin Support Automatic Atlas Export

[drelaptop]

Demand from developers, record

For example, we dragged 5 pictures to the editor! Create an automatic atlas configuration in this folder, look at the package directory, only see a large picture of the plist, we use or to use the thumbnail, do not have to re-map every time you change a map
Refer to Creator's Auto Atlas Configuration

开发者提出的需求，记录一下

比如我们拖拽了5张图片到编辑器！在这个文件夹下创建个自动图集配置、在打包的时候看打包目录下只会有一张plist的大图，我们使用还是以小图的方式使用、不用每换一张图一直重新打大图
可参考 Creator 的自动图集配置

[minggo]

Please use english.

[minggo]

You can keep the message from developers, but yourself should use english.