(core) Add account page option to allow Google login

Summary:
Enabled by default, the new checkbox is only visible to
users logged in with email/password, and controls whether it is possible
to log in to the same account via a Google account
(with matching email). When disabled, CognitoClient will refuse logins
from Google if a Grist account with the same email exists.

Test Plan:
Server and browser tests for setting flag. Manual tests to verify
Cognito doesn't allow signing in with Google when flag is disabled.

Reviewers: paulfitz

Reviewed By: paulfitz

Differential Revision: https://phab.getgrist.com/D3257

app/common/LoginSessionAPI.ts

@@ -11,6 +11,7 @@ export interface UserProfile {
 // have been validated against database.
 export interface FullUser extends UserProfile {
   id: number;
+  allowGoogleLogin?: boolean; // when present, specifies whether logging in via Google is possible.
 }
 
 export interface LoginSessionAPI {

app/common/UserAPI.ts

@@ -131,6 +131,12 @@ export interface Document extends DocumentProperties {
   trunkAccess?: roles.Role|null;
 }
 
+// Non-core options for a user.
+export interface UserOptions {
+  // Whether signing in with Google is allowed. Defaults to true if unset.
+  allowGoogleLogin?: boolean;
+}
+
 export interface PermissionDelta {
   maxInheritedRole?: roles.BasicRole|null;
   users?: {
@@ -357,6 +363,7 @@ export interface UserAPI {
   getUserProfile(): Promise<FullUser>;
   getUserMfaPreferences(): Promise<UserMFAPreferences>;
   updateUserName(name: string): Promise<void>;
+  updateAllowGoogleLogin(allowGoogleLogin: boolean): Promise<void>;
   getWorker(key: string): Promise<string>;
   getWorkerAPI(key: string): Promise<DocWorkerAPI>;
   getBillingAPI(): BillingAPI;
@@ -653,6 +660,13 @@ export class UserAPIImpl extends BaseAPI implements UserAPI {
     });
   }
 
+  public async updateAllowGoogleLogin(allowGoogleLogin: boolean): Promise<void> {
+    await this.request(`${this._url}/api/profile/allowGoogleLogin`, {
+      method: 'POST',
+      body: JSON.stringify({allowGoogleLogin})
+    });
+  }
+
   public async getWorker(key: string): Promise<string> {
     const json = await this.requestJson(`${this._url}/api/worker/${key}`, {
       method: 'GET',