LibGfx: Add initial ISO BMFF parsing and a utility to print file info

Currently, the `isobmff` utility will only print the media file type
info from the FileTypeBox (major brand and compatible brands), as well
as the names and sizes of top-level boxes.

Userland/Libraries/LibGfx/ImageFormats/ISOBMFF/Boxes.h

@@ -0,0 +1,96 @@
+/*
+ * Copyright (c) 2023, Gregory Bertilson <Zaggy1024@gmail.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/Endian.h>
+#include <AK/NonnullOwnPtr.h>
+#include <AK/String.h>
+#include <AK/Traits.h>
+#include <AK/Vector.h>
+#include <LibVideo/DecoderError.h>
+
+#include "BoxStream.h"
+#include "Enums.h"
+
+namespace Gfx::ISOBMFF {
+
+// ISO/IEC 14496-12 Fifth Edition
+
+// 4.2 Object Structure
+struct BoxHeader {
+    BoxType type { BoxType::None };
+    u64 contents_size { 0 };
+};
+
+ErrorOr<BoxHeader> read_box_header(Stream& stream);
+
+struct Box {
+    Box() = default;
+    virtual ~Box() = default;
+    virtual ErrorOr<void> read_from_stream(BoxStream&) { return {}; }
+    virtual BoxType box_type() const { return BoxType::None; }
+    virtual void dump(String const& prepend = {}) const;
+};
+
+using BoxList = Vector<NonnullOwnPtr<Box>>;
+
+struct FullBox : public Box {
+    virtual ErrorOr<void> read_from_stream(BoxStream& stream) override;
+    virtual void dump(String const& prepend = {}) const override;
+
+    u8 version { 0 };
+    u32 flags { 0 };
+};
+
+struct UnknownBox final : public Box {
+    static ErrorOr<NonnullOwnPtr<UnknownBox>> create_from_stream(BoxType type, BoxStream& stream)
+    {
+        auto box = TRY(try_make<UnknownBox>(type, stream.remaining()));
+        TRY(box->read_from_stream(stream));
+        return box;
+    }
+    UnknownBox(BoxType type, size_t contents_size)
+        : m_box_type(type)
+        , m_contents_size(contents_size)
+    {
+    }
+    virtual ~UnknownBox() override = default;
+    virtual ErrorOr<void> read_from_stream(BoxStream&) override;
+    virtual BoxType box_type() const override { return m_box_type; }
+    virtual void dump(String const& prepend = {}) const override;
+
+private:
+    BoxType m_box_type { BoxType::None };
+    size_t m_contents_size { 0 };
+};
+
+#define BOX_SUBTYPE(BoxName)                                                     \
+    static ErrorOr<NonnullOwnPtr<BoxName>> create_from_stream(BoxStream& stream) \
+    {                                                                            \
+        auto box = TRY(try_make<BoxName>());                                     \
+        TRY(box->read_from_stream(stream));                                      \
+        return box;                                                              \
+    }                                                                            \
+    BoxName() = default;                                                         \
+    virtual ~BoxName() override = default;                                       \
+    virtual ErrorOr<void> read_from_stream(BoxStream& stream) override;          \
+    virtual BoxType box_type() const override                                    \
+    {                                                                            \
+        return BoxType::BoxName;                                                 \
+    }                                                                            \
+    virtual void dump(String const& prepend = {}) const override;
+
+// 4.3 File Type Box
+struct FileTypeBox final : public FullBox {
+    BOX_SUBTYPE(FileTypeBox);
+
+    BrandIdentifier major_brand { BrandIdentifier::None };
+    u32 minor_version;
+    Vector<BrandIdentifier> compatible_brands;
+};
+
+}