Added FS functions to Archive and Archive_RomFS

Added pack_u32 and unpack_u64 helper functions to math_util.h
Not sure about the endian safeness about this, but:

    struct Input {
        u32 pad0;
        u64 offset;
        u32 length;
        u32 pad1;
        u32 address;
    } input = *(Input*)cmd_buff;