perf(ext/node): native vectored write for server streams (#19752)

```
# main
$ ./load_test 10 0.0.0.0 8080 0 0
Using message size of 20 bytes
Running benchmark now...
Msg/sec: 106182.250000
Msg/sec: 110279.750000
^C

# this PR
$ ./load_test 10 0.0.0.0 8080 0 0
Using message size of 20 bytes
Running benchmark now...
Msg/sec: 131632.250000
Msg/sec: 134754.250000
^C
```

1 files changed, 29 insertions, 1 deletions

diff --git a/ext/node/polyfills/internal_binding/stream_wrap.ts b/ext/node/polyfills/internal_binding/stream_wrap.ts
index 27870b20b..95f60fe95 100644
--- a/ext/node/polyfills/internal_binding/stream_wrap.ts
+++ b/ext/node/polyfills/internal_binding/stream_wrap.ts
@@ -40,6 +40,9 @@ import {
 } from "ext:deno_node/internal_binding/async_wrap.ts";
 import { codeMap } from "ext:deno_node/internal_binding/uv.ts";
 
+const core = globalThis.Deno.core;
+const { ops } = core;
+
 interface Reader {
   read(p: Uint8Array): Promise<number | null>;
 }
@@ -54,7 +57,7 @@ export interface Closer {
 
 type Ref = { ref(): void; unref(): void };
 
-enum StreamBaseStateFields {
+const enum StreamBaseStateFields {
   kReadBytesOrError,
   kArrayBufferOffset,
   kBytesWritten,
@@ -195,6 +198,31 @@ export class LibuvStreamWrap extends HandleWrap {
     chunks: Buffer[] | (string | Buffer)[],
     allBuffers: boolean,
   ): number {
+    const supportsWritev = this.provider === providerType.TCPSERVERWRAP;
+    // Fast case optimization: two chunks, and all buffers.
+    if (chunks.length === 2 && allBuffers && supportsWritev) {
+      // String chunks.
+      if (typeof chunks[0] === "string") chunks[0] = Buffer.from(chunks[0]);
+      if (typeof chunks[1] === "string") chunks[1] = Buffer.from(chunks[1]);
+
+      ops.op_raw_write_vectored(
+        this[kStreamBaseField]!.rid,
+        chunks[0],
+        chunks[1],
+      ).then((nwritten) => {
+        try {
+          req.oncomplete(0);
+        } catch {
+          // swallow callback errors.
+        }
+
+        streamBaseState[kBytesWritten] = nwritten;
+        this.bytesWritten += nwritten;
+      });
+
+      return 0;
+    }
+
     const count = allBuffers ? chunks.length : chunks.length >> 1;
     const buffers: Buffer[] = new Array(count);