QOI file support.

[sloganking]

QOI images can be decoded 4-5x faster than PNG images. This makes them ideal for this tile-image-viewer, as it would allow us to load in tiles 4-5x faster.

It would be easiest to do this by waiting for qoi support from the image crate.
image-rs/image#1641

[sloganking]

Per image-rs/image#1641 the image crate now supports the qoi file format. The test commit c91a680 shows a way to add qoi support, but it is not performance optimal since macroquad does not support qoi.