Add _pywwtExpedite tags for pywwt's Jupyter async skullduggery

In order for user code to be able to interact with WWT with proper async
characteristics, we need to hack the Python kernel to expedite
processing of WWT messages, for reasons laid out in detail in the
corresponding pywwt code. Here we add the special tag that requests
expedited processing. If the kernel isn't hacked, then nothing unusual
happens.

src/comms.ts

@@ -93,6 +93,7 @@ export class WWTLabCommManager {
       // Send some startup information to the kernel.
       try {
         comm.send({
+          content: { _pywwtExpedite: true },
           type: 'wwt_jupyter_startup_info',
           dataRelayConfirmedAvailable: this.dataRelayConfirmedAvailable
         });
@@ -129,6 +130,9 @@ export class WWTLabCommManager {
       return;
     }
 
+    d = Object.assign({ content: {} }, d);
+    (d['content'] as any)['_pywwtExpedite'] = true; // eslint-disable-line @typescript-eslint/no-explicit-any
+
     // OK, this is a generic message.
 
     const toRemove: string[] = [];
@@ -171,6 +175,7 @@ export class WWTLabCommManager {
 
     const toRemove: string[] = [];
     const msg = {
+      content: { _pywwtExpedite: true },
       type: 'wwt_jupyter_viewer_status',
       alive: appAlive
     };

src/viewer.ts

@@ -11,7 +11,8 @@ import { WWTLabCommManager } from './comms';
 
 // TODO: make runtime configurable
 // XXX: hardcoding "latest"
-const IFRAME_URL = 'https://web.wwtassets.org/research/latest/';
+//const IFRAME_URL = 'https://web.wwtassets.org/research/latest/';
+const IFRAME_URL = 'http://localhost:8080/';
 
 export class WWTLabViewer extends Widget {
   private readonly comms: WWTLabCommManager;