LibGfx: Allow extracting paths from fonts and add Gfx::Path::text()

This updates fonts so rather than rastering directly to a bitmap, you
can extract paths for glyphs. This is then used to implement a
Gfx::Path::text("some text", font) API, that if given a vector font
appends the path of the text to your Gfx::Path. This then allows
arbitrary manipulation of the text (rotation, skewing, etc), paving the
way for Word Art in Serenity.

Userland/Libraries/LibGfx/Path.h

@@ -10,6 +10,7 @@
 #include <AK/HashMap.h>
 #include <AK/Optional.h>
 #include <AK/Vector.h>
+#include <LibGfx/Font/Font.h>
 #include <LibGfx/Forward.h>
 #include <LibGfx/Line.h>
 #include <LibGfx/Point.h>
@@ -153,6 +154,8 @@ public:
         elliptical_arc_to(point, { radius, radius }, 0, large_arc, sweep);
     }
 
+    void text(Utf8View, Font const&);
+
     FloatPoint last_point();
 
     void close();