[💫 Feature Request ] Allow SSE to use POST /w payload

There is no technical reason to prevent SSE from sending a _POST_ request or limiting the API to be **_payload-less_**

This issue is a very modest request to allow more advanced payloads for SSE.

I looked for existing implimentations and found [This](https://github.com/mpetazzoni/sse.js/blob/main/lib/sse.js)

I've already integrated it as an EventSource drop-in replacement to SSE and it works great.

Upon adding a payload (namely a captcha) and making it a POST request, everything works as expected and is very stable.

Would it be possible to integrate htmx 2.0 SSE extention with this solution?

Check https://dbounce.me (Bulk verification) for a working example.