test: add http agent to executionAsyncResource

I added a testcase about executionAsyncResource with Http Agent.

Refs: https://github.com/nodejs/node/blob/master/test/async-hooks/test-async-exec-resource-http.js
Signed-off-by: psj-tar-gz <lyricalllmagical@gmail.com>

test/async-hooks/test-async-exec-resource-http-agent.js

@@ -0,0 +1,35 @@
+'use strict';
+
+const assert = require('assert');
+
+const {
+  executionAsyncResource,
+  executionAsyncId,
+  createHook,
+} = require('async_hooks');
+const http = require('http');
+
+const hooked = {};
+createHook({
+  init(asyncId, type, triggerAsyncId, resource) {
+    hooked[asyncId] = resource;
+  }
+}).enable();
+
+const agent = new http.Agent({
+    maxSockets: 1
+  });
+
+const server = http.createServer((req, res) => {
+  res.end('ok');
+});
+
+server.listen(0, () => {
+    assert.strictEqual(executionAsyncResource(), hooked[executionAsyncId()]);
+
+    http.get({ agent, port: server.address().port }, () => {
+      assert.strictEqual(executionAsyncResource(), hooked[executionAsyncId()]);
+      server.close();
+      agent.destroy();
+    });
+});