Support more image formats for icons.

[K0-RR]

It would be nice to be able to use some newer formats like webp for icons. Support for gifs like on the curseforge would also be great.

[K0-RR]

What about vector graphics?

[liach]

Hmm, currently this is the only api exposed for getting the icon: https://github.com/FabricMC/fabric-loader/blob/4d40bf7e06bfdc73363e75ecbed12866705d9175/src/main/java/net/fabricmc/loader/api/metadata/ModMetadata.java#L170

It currently just returns an arbitrary path. If we do intend to reuse that, we can probably examine the icon type by checking that path's extension (file suffix like .png etc.) but we might want another api that returns the icon by type as well.

[naciacia]

Please?