LibWeb: Port IDL implementations Blob and File to new String

Author: https://github.com/kennethmyhra
Commit: 9a5a8d617d
Pull-request: https://github.com/SerenityOS/serenity/pull/17614
Reviewed-by: https://github.com/linusg ✅

Userland/Libraries/LibWeb/FileAPI/Blob.idl

@@ -1,4 +1,4 @@
-[Exposed=(Window,Worker), Serializable]
+[Exposed=(Window,Worker), Serializable, UseNewAKString]
 interface Blob {
     constructor(optional sequence<BlobPart> blobParts, optional BlobPropertyBag options = {});