Add the missing echo native module for testing.

Author: ShaleXIONG

crates/execution-engine/src/native_modules/echo.rs

@@ -0,0 +1,23 @@
+use crate::native_modules::common::StaticNativeModule;
+use anyhow::Result;
+use std::{path::Path, fs::{read, write}};
+
+pub(crate) struct EchoService;
+
+impl StaticNativeModule for EchoService {
+    fn name(&self) -> &str {
+        "Echo Service"
+    }
+
+    fn serve(&mut self, input: &Path, output: &Path) -> Result<()> {
+        let buf = read(input)?;
+        write(output, buf)?;
+        Ok(())
+    }
+}
+
+impl EchoService {
+    pub(crate) fn new() -> Self {
+        Self {}
+    }
+}