tests: add bombardier e2e tests

benchmark/e2e.txt

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+node ./benchmark/server.js
+bombardier --body-file="./README.md" --method=POST --duration=10s --connections=100 http://localhost:3000/api/upload 
+
+
+
+

benchmark/server.js

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+// inital copy of with-http.js
+// made a copy so that examples can be changed without impacting tests
+import http from 'node:http';
+import slugify from '@sindresorhus/slugify';
+import formidable, {errors as formidableErrors} from '../src/index.js';
+
+const server = http.createServer((req, res) => {
+  // handle common internet errors
+  // to avoid server crash
+  req.on('error', console.error);
+  res.on('error', console.error);
+
+
+  if (req.url === '/api/upload' && req.method.toLowerCase() === 'post') {
+    const form = formidable({
+      uploadDir: `benchmark/testuploads`,
+      keepExtensions: true,
+    });
+
+    form.parse(req, (err, fields, files) => {
+      if (err) {
+        console.error(err);
+        res.writeHead(err.httpCode || 400, { 'Content-Type': 'text/plain' });
+        res.end(String(err));
+        return;
+      }
+      res.writeHead(200, { 'Content-Type': 'application/json' });
+      res.end(JSON.stringify({ fields, files }, null, 2));
+    });
+
+    return;
+  }
+
+  // else not used in tests
+
+});
+
+server.listen(3000, () => {
+  console.log('Server listening on http://localhost:3000 ...');
+});

benchmark/testuploads/note.txt

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+File to force directory existence in git