(core) Enable MFA configuration (and add SMS)

Summary:
Enables configuration of multi-factor authentication from the
account page (for users who sign in with email/password), and adds
SMS as an authentication method.

Test Plan: Project, browser and server tests.

Reviewers: paulfitz

Reviewed By: paulfitz

Differential Revision: https://phab.getgrist.com/D3215

app/client/ui/setupPage.ts

@@ -0,0 +1,21 @@
+import {AppModel, TopAppModelImpl} from 'app/client/models/AppModel';
+import {setUpErrorHandling} from 'app/client/models/errors';
+import {buildSnackbarDom} from 'app/client/ui/NotifyUI';
+import {addViewportTag} from 'app/client/ui/viewport';
+import {attachCssRootVars} from 'app/client/ui2018/cssVars';
+import {dom, DomContents} from 'grainjs';
+
+/**
+ * Sets up error handling and global styles, and replaces the DOM body with
+ * the result of calling `buildPage`.
+ */
+export function setupPage(buildPage: (appModel: AppModel) => DomContents) {
+  setUpErrorHandling();
+  const topAppModel = TopAppModelImpl.create(null, {});
+  attachCssRootVars(topAppModel.productFlavor);
+  addViewportTag();
+  dom.update(document.body, dom.maybe(topAppModel.appObs, (appModel) => [
+    buildPage(appModel),
+    buildSnackbarDom(appModel.notifier, appModel),
+  ]));
+}