(core) Polish tutorial popups

Summary:
Includes the following changes:
 *  Adds "Click to expand" hover tooltip to all images
 *  Adds support for minimize/maximize by double clicking tutorial popup header
 *  Add New menu (and all other popups) should now persist when user moves tutorial popup
 *  Preserves scrollbar position when minimizing and maximizing tutorial popup
 *  Formula cell editor (and other elements) should now be stacked under tutorial

Test Plan: Browser and manual tests.

Reviewers: jarek

Reviewed By: jarek

Differential Revision: https://phab.getgrist.com/D3864

app/client/ui/ApiKey.ts

@@ -115,8 +115,12 @@ export class ApiKey extends Disposable {
     confirmModal(
       t("Remove API Key"), t("Remove"),
       () => this._onDelete(),
-      t("You're about to delete an API key. This will cause all future requests " +
-        "using this API key to be rejected. Do you still want to delete?")
+      {
+        explanation: t(
+          "You're about to delete an API key. This will cause all future requests " +
+          "using this API key to be rejected. Do you still want to delete?"
+        ),
+      }
     );
   }
 }