feat: add two factor auth (#643)

Add two factor authentication for users who wish to enhance the security of their accounts.

packages/lib/server-only/2fa/is-2fa-availble.ts

@@ -0,0 +1,17 @@
+import { User } from '@documenso/prisma/client';
+
+import { DOCUMENSO_ENCRYPTION_KEY } from '../../constants/crypto';
+
+type IsTwoFactorAuthenticationEnabledOptions = {
+  user: User;
+};
+
+export const isTwoFactorAuthenticationEnabled = ({
+  user,
+}: IsTwoFactorAuthenticationEnabledOptions) => {
+  return (
+    user.twoFactorEnabled &&
+    user.identityProvider === 'DOCUMENSO' &&
+    typeof DOCUMENSO_ENCRYPTION_KEY === 'string'
+  );
+};