unwrap netty WriteTask (#7822)

Author: richardstartin

dd-java-agent/instrumentation/java-concurrent/src/main/java/datadog/trace/instrumentation/java/concurrent/TaskUnwrappingInstrumentation.java

@@ -49,11 +49,15 @@ public boolean isEnabled() {
     "task",
     "io.netty.util.concurrent.PromiseTask",
     "task",
+    "io.netty.channel.AbstractChannelHandlerContext$WriteTask",
+    "msg",
     // netty shaded into gRPC
     "io.grpc.netty.shaded.io.netty.util.concurrent.PromiseTask$RunnableAdapter",
     "task",
     "io.grpc.netty.shaded.io.netty.util.concurrent.PromiseTask",
     "task",
+    "io.grpc.netty.shaded.io.netty.channel.AbstractChannelHandlerContext$WriteTask",
+    "msg",
     "io.grpc.Context$1",
     "val$r",
     "io.grpc.Context$2",