Meta: Add ImageFormats/JPEGWriter.cpp to gn build

Author: krkk

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/JPEGWriter.cpp",
     "ImageFormats/JPEGXLLoader.cpp",
     "ImageFormats/PBMLoader.cpp",
     "ImageFormats/PGMLoader.cpp",