(core) Delete my account button

Summary:
Adding new "Delete my account" button to the profile page that allows users to remove completely
their accounts as long as they don't own any team site.

Test Plan: Added

Reviewers: georgegevoian, paulfitz

Reviewed By: georgegevoian, paulfitz

Subscribers: paulfitz

Differential Revision: https://phab.getgrist.com/D4037

stubs/app/client/ui/DeleteAccountDialog.ts

@@ -0,0 +1,11 @@
+import {FullUser} from 'app/common/UserAPI';
+import {Disposable} from 'grainjs';
+
+export class DeleteAccountDialog extends Disposable {
+  constructor(appModel: FullUser) {
+    super();
+  }
+  public buildDom() {
+    return null;
+  }
+}