Meta: Port recent build changes to gn build

This ports the following commits:

e8a63eeb0e8e6b64b2071d119526057909e5f8db
bec07d4af7892818055eb2277b680fc3267feae4
0e125035869242b7bd24013aab87b1b015a10dc3

Meta/gn/secondary/Userland/Libraries/LibGfx/BUILD.gn

@@ -43,6 +43,7 @@ shared_library("LibGfx") {
     "ImageFormats/ICOLoader.cpp",
     "ImageFormats/ImageDecoder.cpp",
     "ImageFormats/JPEGLoader.cpp",
+    "ImageFormats/JPEGXLLoader.cpp",
     "ImageFormats/PBMLoader.cpp",
     "ImageFormats/PGMLoader.cpp",
     "ImageFormats/PNGLoader.cpp",

Meta/gn/secondary/Userland/Libraries/LibWeb/BUILD.gn

@@ -250,6 +250,7 @@ shared_library("LibWeb") {
     "Dump.cpp",
     "FontCache.cpp",
     "Namespace.cpp",
+    "PixelUnits.cpp",
   ]
   deps = [
            ":all_generated",

Meta/gn/secondary/Userland/Libraries/LibWeb/SVG/BUILD.gn

@@ -29,7 +29,10 @@ source_set("SVG") {
     "SVGStopElement.cpp",
     "SVGStyleElement.cpp",
     "SVGSymbolElement.cpp",
+    "SVGTSpanElement.cpp",
     "SVGTextContentElement.cpp",
+    "SVGTextElement.cpp",
+    "SVGTextPositioningElement.cpp",
     "SVGTitleElement.cpp",
     "SVGUseElement.cpp",
     "TagNames.cpp",

Meta/gn/secondary/Userland/Libraries/LibWeb/idl_files.gni

@@ -239,8 +239,11 @@ standard_idl_files = [
   "//Userland/Libraries/LibWeb/SVG/SVGStopElement.idl",
   "//Userland/Libraries/LibWeb/SVG/SVGStyleElement.idl",
   "//Userland/Libraries/LibWeb/SVG/SVGSymbolElement.idl",
+  "//Userland/Libraries/LibWeb/SVG/SVGTextElement.idl",
   "//Userland/Libraries/LibWeb/SVG/SVGTextContentElement.idl",
+  "//Userland/Libraries/LibWeb/SVG/SVGTextPositioningElement.idl",
   "//Userland/Libraries/LibWeb/SVG/SVGTitleElement.idl",
+  "//Userland/Libraries/LibWeb/SVG/SVGTSpanElement.idl",
   "//Userland/Libraries/LibWeb/SVG/SVGUseElement.idl",
   "//Userland/Libraries/LibWeb/Selection/Selection.idl",
   "//Userland/Libraries/LibWeb/UIEvents/FocusEvent.idl",