Add support of PixiInspector

[CyberDex]

To make it work, we need to expose PIXI.Application instance to a globalThis.

This will let all stories be open to debug and investigate in the Pixi layout perspective.

[Zyie]

@CyberDex you can access the app using the startup method

return { 
    view: button.view, 
    resize: () => centerElement(buttonView), 
    startup: (app) => {
        globalThis.PIXI_APP = app;
    }  
};

[CyberDex]

@Zyie as a developer, yes, but it can be helpful to the people, that will learn those stories. They can use pixi inspector to check what is the layout structure, that is created under the hood using the story code.