Export icon information in mods command

[cl8n]

so that osu-web can render the icons without maintaining its own images etc.

not useful without ppy/osu#22175 and support on osu-web (haven't finished this yet, going to see how the osu PR goes first)

[peppy]

I'm not sure about consuming the FontAwesome icons instead of replacing them all into one consistent set (and only exposing an icon name, or even better, nothing at all)... but maybe this is okay?

@smoogipoo @arflyte thoughts? icons are all over the place right now.

[smoogipoo]

I don't have any strong opinions either way as this can be changed later and any solution should be as minimal overhead as possible for us to continue progressing on the game rather than tooling.

[cl8n]

with the new suggested direction to not use icon fonts for mods, this would be unnecessary. for mods currently using fontawesome icons I plan to swap them to images all the same (maybe just web-side for that part... either way, point stands here).