inprocess: add a toString for InProcessSocketAddress

The motivation here is in some cases we log the remote-addr that is set in the gRPC call attributes, and have to special case this type to support inprocess servers.

core/src/main/java/io/grpc/inprocess/InProcessSocketAddress.java

@@ -33,4 +33,9 @@ public final class InProcessSocketAddress extends SocketAddress {
   public String getName() {
     return name;
   }
+  
+  @Override
+  public String toString() {
+    return name;
+  }
 }