(core) Enable auto triggering of Welcome Tour, and various improvements.

Summary:
- Add showGristTour preference, and trigger tour automatically.
- Tour is only triggered for new and anonymous users on a personal org, with
  edit permission.

- Automatically open the right panel at tour start.
- Don't show tours on mobile, since that's not ready (popups are cut off
  and can't be dismissed)
- Cancel previous tour if a new one is somehow started.
- Remove #repeat- trigger hash tags from the URL when the tour starts.
- Ensure Help Center popup is positioned even when left panel is collapsed.
- Polish up the content of the last two cards in the tour.

Test Plan: Added test case for triggering and opening right panel.

Reviewers: alexmojaki, paulfitz

Reviewed By: alexmojaki

Differential Revision: https://phab.getgrist.com/D2955

app/client/ui/OnBoardingPopups.ts

@@ -22,7 +22,7 @@
  *   the caller. Pass an `onFinishCB` to handle when a user dimiss the popups.
  */
 
-import { Disposable, dom, DomElementArg, makeTestId, styled, svg } from "grainjs";
+import { Disposable, dom, DomElementArg, Holder, makeTestId, styled, svg } from "grainjs";
 import { createPopper, Placement } from '@popperjs/core';
 import { FocusLayer } from 'app/client/lib/FocusLayer';
 import * as Mousetrap from 'app/client/lib/Mousetrap';
@@ -71,8 +71,12 @@ export interface IOnBoardingMsg {
   urlState?: IGristUrlState;
 }
 
+// There should only be one tour at a time. Use a holder to dispose the previous tour when
+// starting a new one.
+const tourSingleton = Holder.create<OnBoardingPopupsCtl>(null);
+
 export function startOnBoarding(messages: IOnBoardingMsg[], onFinishCB: () => void) {
-  const ctl = new OnBoardingPopupsCtl(messages, onFinishCB);
+  const ctl = OnBoardingPopupsCtl.create(tourSingleton, messages, onFinishCB);
   ctl.start().catch(reportError);
 }