(core) Focusing the creator panel on the table wiget for charts and custom views

Summary:
When a chart page/section is added and the creator panel is already open, focus is set to a "table" tab.
When a custom view is added as a page/section, the same thing happens, but there is also a behavioral tooltip shown
for the custom URL.

Test Plan: Updated and added.

Reviewers: georgegevoian

Reviewed By: georgegevoian

Differential Revision: https://phab.getgrist.com/D3857

app/common/Prefs.ts

@@ -86,6 +86,7 @@ export const BehavioralPrompt = StringUnion(
   'editCardLayout',
   'addNew',
   'rickRow',
+  'customURL',
 );
 export type BehavioralPrompt = typeof BehavioralPrompt.type;
 

app/common/gristUrls.ts

@@ -70,6 +70,7 @@ export const commonUrls = {
   helpUnderstandingReferenceColumns: "https://support.getgrist.com/col-refs/#understanding-reference-columns",
   helpTriggerFormulas: "https://support.getgrist.com/formulas/#trigger-formulas",
   helpTryingOutChanges: "https://support.getgrist.com/copying-docs/#trying-out-changes",
+  helpCustomWidgets: "https://support.getgrist.com/widget-custom",
   plans: "https://www.getgrist.com/pricing",
   createTeamSite: "https://www.getgrist.com/create-team-site",
   sproutsProgram: "https://www.getgrist.com/sprouts-program",