Change LoginHandler response to always use JSON, add token-grabber.js example for interacting with the login API.

docs/examples/token-grabber.js

@@ -0,0 +1,23 @@
+import readline from 'readline/promises';
+import { stdin as input, stdout as output } from 'process';
+
+const rl = readline.createInterface({ input, output });
+
+const username = await rl.question('Please enter your username: ');
+const password = await rl.question('Please enter your password: ');
+
+rl.close();
+
+const loginResponse = await fetch('http://localhost:8080/login', {
+  method: 'POST',
+  headers: { 'Content-Type': 'application/json' },
+  body: JSON.stringify({ username, password })
+});
+
+const data = await loginResponse.json();
+if (data.success != 'true') {
+  console.log(`Login not successful: ${data.message}`);
+  process.exit(1);
+}
+const sessionID = data.sessionId;
+console.log(`Your token is: ${sessionID}`);