feat: add plugin

- add plugin system that request may included to run before do actual request by type.

Signed-off-by: Pakin <pakin.t@forth.co.th>

plugins/example-js/index.js

@@ -0,0 +1,18 @@
+export const handler = {
+  processMessage(input) {
+    // input should be { type_w: "...", "payload": { plugin: "", ... } }
+    let n_input = JSON.parse(input);
+    console.log(`processing: ${input}`);
+    try {
+      // delete n_input["payload"]["plugin"];
+      return JSON.stringify({
+        type_w: n_input.type,
+        payload: n_input.payload
+      });
+    } catch (e) {
+      return `JSERROR: ${e.message}\nStack: ${e.stack}`;
+    }
+
+
+  }
+};