LibGfx: Make formatting of spatial types work with non-int/floats

Line, Point, Rect, and Size now all have Formatters that will work with
any type that itself has a Formatter.

Userland/Libraries/LibGfx/Line.h

@@ -6,6 +6,7 @@
 
 #pragma once
 
+#include <AK/Format.h>
 #include <AK/Optional.h>
 #include <AK/StdLibExtras.h>
 #include <AK/String.h>
@@ -153,3 +154,15 @@ inline String FloatLine::to_string() const
 }
 
 }
+
+namespace AK {
+
+template<typename T>
+struct Formatter<Gfx::Line<T>> : Formatter<FormatString> {
+    ErrorOr<void> format(FormatBuilder& builder, Gfx::Line<T> const& value)
+    {
+        return Formatter<FormatString>::format(builder, "[{},{} -> {},{}]"sv, value.a().x(), value.a().y(), value.b().x(), value.b().y());
+    }
+};
+
+}