LibWeb: Add missing Page.h include to SVGDecodedImageData

The PageClient for SVGDecodedImageData needs to actually have the
definition of PageClient available in order to inherit from it. This
fixes importing this header from Objective-C or Swift.

Userland/Libraries/LibWeb/SVG/SVGDecodedImageData.h

@@ -8,6 +8,7 @@
 
 #include <LibWeb/DOM/Document.h>
 #include <LibWeb/HTML/DecodedImageData.h>
+#include <LibWeb/Page/Page.h>
 
 namespace Web::SVG {