[Examples Gallery][New example]: Uploading files in Deno Deploy

Hi.

If possible, I would like to add the following example to the area `Examples Gallery` at the page https://deno.com/deploy/docs/examples:

```typescript
import * as path from "https://deno.land/std@0.173.0/path/mod.ts";
import { serve } from "https://deno.land/std@0.173.0/http/server.ts";
import { serveFile } from "https://deno.land/std@0.173.0/http/file_server.ts";

const UPLOADS_DIR = "./";

const html = `

Submit

`;

const headers = { "content-type": "text/html; charset=utf-8" };

async function handler(req: Request): Promise {
switch (req.method) {
case "GET": {
const url = new URL(req.url);
const fileName = url.searchParams.get("file");
if (fileName) {
return serveFile(req, path.join(UPLOADS_DIR, fileName));
}
return new Response(html, { headers });
}

case "POST": {
const form = await req.formData();
const upload = form.get("upload") as File;
if (!upload.name) {
return new Response("No file sent", { headers, status: 400 });
}
const file = await Deno.open(path.join(UPLOADS_DIR, upload.name), {
create: true,
write: true,
truncate: true,
});
upload.stream().pipeTo(file.writable);
return new Response(
`File saved ${upload.name}`,
{ headers }
);
}

default:
return new Response("Invalid method", { status: 405 });
}
}

serve(handler);
```

TIA

Start at the Examples Gallery page linked in the issue and inspect how existing examples are organized. Compare the supplied TypeScript upload example with those entries, then add it in the matching location and verify that the new example appears on the page and demonstrates file uploading in Deno Deploy.

Written by the indexing model from the issue text.