Add echo command

src/cli.rs

@@ -210,6 +210,7 @@ pub async fn cli() -> Result<(), Box<dyn Error>> {
             per_item_command(Open),
             per_item_command(Post),
             per_item_command(Where),
+            per_item_command(Echo),
             whole_stream_command(Config),
             whole_stream_command(SkipWhile),
             per_item_command(Enter),