multiboot2: cleanup of debug format output

[phip1611]

Debug output of the Multiboot2 Boot Info is now much nicer. All tags appear in alphabetical order. Example taken from the integration test:

Multiboot2BootInformation {
    start_address: 0x1065a8,
    end_address: 0x1068e8,
    total_size: 0x340,
    basic_memory_info: Some(
        BasicMemoryInfoTag {
            typ: BasicMeminfo,
            size: 0x10,
            memory_lower: 0x27f,
            memory_upper: 0x5b80,
        },
    ),
    boot_loader_name: Some(
        BootLoaderNameTag {
            typ: BootLoaderName,
            size: 0x12,
            name: Ok(
                "GRUB 2.06",
            ),
        },
    ),
    command_line: Some(
        CommandLineTag {
            typ: Cmdline,
            size: 0x23,
            cmdline: Ok(
                "some commandline arguments",
            ),
        },
    ),
    efi_bs_not_exited: None,
    efi_memory_map: None,
    efi_sdt_32: None,
    efi_sdt_64: None,
    efi_ih_32: None,
    efi_ih_64: None,
    elf_sections (count): 0x8,
    framebuffer: Some(
        Ok(
            FramebufferTag {
                typ: Framebuffer,
                size: 0x20,
                buffer_type: Ok(
                    Text,
                ),
                address: 0xb8000,
                pitch: 0xa0,
                width: 0x50,
                height: 0x19,
                bpp: 0x10,
            },
        ),
    ),
    load_base_addr: Some(
        ImageLoadPhysAddrTag {
            typ: LoadBaseAddr,
            size: 0xc,
            load_base_addr: 0x1000000,
        },
    ),
    memory_map: Some(
        MemoryMapTag {
            typ: Mmap,
            size: 0xb8,
            entry_size: 0x18,
            entry_version: 0x0,
            areas: [
                MemoryArea {
                    base_addr: 0x0,
                    length: 0x9fc00,
                    typ: Available,
                },
                MemoryArea {
                    base_addr: 0x9fc00,
                    length: 0x400,
                    typ: Reserved,
                },
                MemoryArea {
                    base_addr: 0xf0000,
                    length: 0x10000,
                    typ: Reserved,
                },
                MemoryArea {
                    base_addr: 0x100000,
                    length: 0x16e0000,
                    typ: Available,
                },
                MemoryArea {
                    base_addr: 0x17e0000,
                    length: 0x20000,
                    typ: Reserved,
                },
                MemoryArea {
                    base_addr: 0xfffc0000,
                    length: 0x40000,
                    typ: Reserved,
                },
                MemoryArea {
                    base_addr: 0xfd00000000,
                    length: 0x300000000,
                    typ: Reserved,
                },
            ],
        },
    ),
    modules: [
        ModuleTag {
            type: Module,
            size: 0x1c,
            mod_start: 0x107000,
            mod_end: 0x107162,
            mod_size: 0x162,
            cmdline: Ok(
                "grub-config",
            ),
        },
    ],
    rsdp_v1: Some(
        RsdpV1Tag {
            typ: AcpiV1,
            size: 0x1c,
            signature: [
                0x52,
                0x53,
                0x44,
                0x20,
                0x50,
                0x54,
                0x52,
                0x20,
            ],
            checksum: 0xcf,
            oem_id: [
                0x42,
                0x4f,
                0x43,
                0x48,
                0x53,
                0x20,
            ],
            revision: 0x0,
            rsdt_address: 0x17e1aea,
        },
    ),
    rsdp_v2: None,
    smbios_tag: None,
    vbe_info_tag: None,
}