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