Support for custom css and custom js for Auto1111

[LEv145]

Auto1111 support custom css file: user.css for adding custom css on startup: https://github.com/AUTOMATIC1111/stable-diffusion-webui/blob/394ffa7b0a7fff3ec484bcd084e673a8b301ccc8/modules/ui_gradio_extensions.py#L48

And if you add the javascript/user.js file, then the js code from there will also be loaded along with auto1111 (It may not have been planned, but it works)

[ssj17vegeta]

Strongly support the idea, since it would allow to hide LORAs located in sub-folders.