use fresher node and debian version (#1255)

This moves to node 22 and debian bookworm, since the versions we've been building and testing with are getting old.

There is some old material kept around for (speaks very quietly) Python 2 (looks around hoping no-one heard) which we continue to support for some long-time users but really really should drop soon.

The changes for the node upgrade were all test related. I did them in a way that shouldn't impair running on older versions of node, and did spot checks for this. This is to give some breathing room for upgrading Grist Lab's grist-saas as follow up work.

app/client/components/GristClientSocket.ts

@@ -71,7 +71,13 @@ export class GristClientSocket {
   }
 
   private _createWSSocket() {
-    if (typeof WebSocket !== 'undefined') {
+    // We used to check if WebSocket was defined here, and use it
+    // if so, secure in the fact that we were in the browser and
+    // the browser would pass along cookie information. But recent
+    // node defines WebSocket, so we narrow down this path to when
+    // a global document is defined (window doesn't work because
+    // some tests mock it).
+    if (typeof document !== 'undefined') {
       this._wsSocket = new WebSocket(this._url);
     } else {
       this._wsSocket = new WS(this._url, undefined, this._options);