(core) suspend a team site after an AppSumo refund

Summary:
This suspends service to a team site for which an AppSumo refund has been made, and nudges users to their free personal account.

I expect that a refund request would fail for a site where user is also paying us for extra seats.

Test Plan: tested manually

Reviewers: dsagal

Reviewed By: dsagal

Differential Revision: https://phab.getgrist.com/D2912

app/client/models/AppModel.ts

@@ -104,7 +104,7 @@ export class TopAppModelImpl extends Disposable implements TopAppModel {
             org.billingAccount.product.name === 'suspended') {
           this.notifier.createUserError(
             'This team site is suspended. Documents can be read, but not modified.',
-            {actions: ['renew']}
+            {actions: ['renew', 'personal']}
           );
         }
       }