[utils] Add .osu parser

[NiceAesth]

Could perhaps integrate with the endpoints that provide .osu files (although I am not a fan of using anything from utils in the clients, instead I think the clients should return BytesIO which utils should accept alongside any file object)

[NiceAesth]

The goal is to eventually handle all osu! filetypes. This may get pushed back as it is relatively low priority and a massive task.

[NiceAesth]

Will leave utils for future milestones.