Add origin checks to web sockets (#6048)

* Move splitOnFirstEquals to util

I will be making use of this to parse the forwarded header.

* Type splitOnFirstEquals with two items

Also add some test cases.

* Check origin header on web sockets

* Update changelog with origin check

* Fix web sockets not closing with error code

src/common/http.ts

@@ -4,6 +4,7 @@ export enum HttpCode {
   NotFound = 404,
   BadRequest = 400,
   Unauthorized = 401,
+  Forbidden = 403,
   LargePayload = 413,
   ServerError = 500,
 }