LibWeb/SVG: Move path data into Path.{h,cpp}

More things need this than just the `<path>` element, so let's avoid
having to include `SVGPathElement.h` in places that don't need it.

Minor changes at the same time:
- Wrap it in a Path class
- Specify underlying type for PathInstructionType
- Make a couple of free functions into methods
- Give PathInstruction an operator==

No functionality changes.

Libraries/LibWeb/SVG/Path.h

@@ -0,0 +1,60 @@
+/*
+ * Copyright (c) 2020, Matthew Olsson <mattco@serenityos.org>
+ * Copyright (c) 2022-2025, Sam Atkins <sam@ladybird.org>
+ * Copyright (c) 2024, Tim Ledbetter <timledbetter@gmail.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/Span.h>
+#include <AK/Types.h>
+#include <AK/Vector.h>
+#include <LibGfx/Forward.h>
+
+namespace Web::SVG {
+
+enum class PathInstructionType : u8 {
+    Move,
+    ClosePath,
+    Line,
+    HorizontalLine,
+    VerticalLine,
+    Curve,
+    SmoothCurve,
+    QuadraticBezierCurve,
+    SmoothQuadraticBezierCurve,
+    EllipticalArc,
+    Invalid,
+};
+
+struct PathInstruction {
+    PathInstructionType type;
+    bool absolute;
+    Vector<float> data;
+
+    bool operator==(PathInstruction const&) const = default;
+
+    void dump() const;
+};
+
+class Path {
+public:
+    Path() = default;
+
+    explicit Path(Vector<PathInstruction> instructions)
+        : m_instructions(move(instructions))
+    {
+    }
+    ReadonlySpan<PathInstruction> instructions() const { return m_instructions; }
+
+    [[nodiscard]] Gfx::Path to_gfx_path() const;
+
+    bool operator==(Path const&) const = default;
+
+private:
+    Vector<PathInstruction> m_instructions;
+};
+
+}