Loading state in web interface

Description

There's currently no loading indication during the ROM loading period.

This is not an issue for small <1MB ROMs, but for larger ones, this can create some confusion for the user.

Build a simple loading status with some vintage looking, taking inspiration from older 8bit games.

Implementation

You can find some inspiration in Dribble and YouTube and create a design.

Implement it at the EmuKit level.

Inspiration