Fix WS/SSE tests and replace go backend with NodeJS (#1876)

* Write WS and SSE test backend in node

* Refactor pages so that the URLs work

* Add tab highlighting script

* Fix stream with multiple events

* Fix highlighting on ext links

* Refactor WS code

* Support event trigger tests

* Add some jitter to the intervals

* Delete old go backend

* Update README with new info and credits

* Update top-level README

* Move ws to dev dependencies

* Remove extraneous go server

* Fix misplace comment

README.md

@@ -102,6 +102,8 @@ At this point you can modify `/src/htmx.js` to add features, and then add tests
 htmx uses the [mocha](https://mochajs.org/) testing framework, the [chai](https://www.chaijs.com/) assertion framework
 and [sinon](https://sinonjs.org/releases/v9/fake-xhr-and-server/) to mock out AJAX requests.  They are all OK.
 
+You can also run live tests and demo of the WebSockets and Server-Side Events extensions with `npm run ws-tests`
+
 ## haiku
 
 *javascript fatigue:<br/>