Add Deno Native Messaging host

Deno exits child process when parent process exits denoland/deno#5501. Use runtime.connectNative().

nm_deno.js

@@ -0,0 +1,60 @@
+#!/usr/bin/env -S ./deno run --allow-run --unstable --v8-flags="--expose-gc,--jitless"
+async function getMessage() {
+  const header = new Uint32Array(1);
+  await Deno.stdin.read(header);
+  const output = new Uint8Array(header[0]);
+  await Deno.stdin.read(output);
+  return output;
+}
+
+async function sendMessage(_) {
+  let message = '';
+  let process = Deno.run({
+    cmd: ['pgrep', '-f', './deno_server.js'],
+    stdout: 'piped',
+    stderr: 'piped',
+  });
+  let rawOutput = await process.output();
+  process.close();
+  if (rawOutput.length) {
+    process = Deno.run({
+      cmd: ['pkill', '-f', './deno_server.js'],
+      stdout: 'null',
+      stderr: 'null',
+    });
+    process.close();
+    message = '"Local server off."';
+  } else {
+    process = Deno.run({
+      cmd: ['./deno_server.js'],
+      stdout: 'null',
+      stderr: 'null',
+    });
+    message = '"Local server on."';
+  }
+  message = new TextEncoder().encode(message);
+  const header = Uint32Array.from(
+    {
+      length: 4,
+    },
+    (_, index) => (message.length >> (index * 8)) & 0xff
+  );
+  const output = new Uint8Array(header.length + message.length);
+  output.set(header, 0);
+  output.set(message, 4);
+  await Deno.stdout.write(output.buffer);
+}
+
+async function main() {
+  while (true) {
+    const message = await getMessage();
+    await sendMessage(message);
+    gc();
+  }
+}
+
+try {
+  main();
+} catch (e) {
+  Deno.exit();
+}