LibWeb: Implement <feImage> SVG filter

Author: https://github.com/tcl3
Commit: d4f05bc4ef
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/5856
Reviewed-by: https://github.com/AtkinsSJ ✅
Reviewed-by: https://github.com/gmta

Libraries/LibWeb/Forward.h

@@ -1051,6 +1051,7 @@ class SVGEllipseElement;
 class SVGFEBlendElement;
 class SVGFEFloodElement;
 class SVGFEGaussianBlurElement;
+class SVGFEImageElement;
 class SVGFilterElement;
 class SVGFitToViewBox;
 class SVGForeignObjectElement;