AK: Add GenericLexer to forwarding header

Author: https://github.com/trflynn89
Commit: https://github.com/SerenityOS/serenity/commit/e331656bb90
Pull-request: https://github.com/SerenityOS/serenity/pull/9499
Reviewed-by: https://github.com/alimpfard
Reviewed-by: https://github.com/davidot ✅

AK/Forward.h

@@ -17,6 +17,7 @@ class ByteBuffer;
 
 class Bitmap;
 using ByteBuffer = AK::Detail::ByteBuffer<32>;
+class GenericLexer;
 class IPv4Address;
 class JsonArray;
 class JsonObject;
@@ -139,6 +140,7 @@ using AK::DuplexMemoryStream;
 using AK::FixedArray;
 using AK::FlyString;
 using AK::Function;
+using AK::GenericLexer;
 using AK::HashMap;
 using AK::HashTable;
 using AK::InputBitStream;