Add the rendering primitives for rendering a path

Right now the path is limited to polygons (only LineTo elements) and only the fill color can be specified.

api/sixtyfps-cpp/include/sixtyfps_pathelements.h

@@ -0,0 +1,34 @@
+#pragma once
+#include <initializer_list>
+#include <string_view>
+#include "sixtyfps_pathelements_internal.h"
+
+namespace sixtyfps {
+
+using internal::types::PathElement;
+
+struct PathElements
+{
+public:
+    using Tag = internal::types::PathElements::Tag;
+
+    PathElements() : data(Data::None()) { }
+    PathElements(const PathElement *firstElement, size_t count)
+        : data(Data::SharedElements(elements_from_array(firstElement, count)))
+    {
+    }
+
+private:
+    static SharedArray<PathElement> elements_from_array(const PathElement *firstElement,
+                                                        size_t count)
+    {
+        SharedArray<PathElement> tmp;
+        sixtyfps_new_path_elements(&tmp, firstElement, count);
+        return tmp;
+    }
+
+    using Data = internal::types::PathElements;
+    Data data;
+};
+
+}