[local-sync] Fix Contact.toJSON

Summary:
We forgot to refactor `publicId` to just `id`, which was breaking contact
deltas in N1.

Test Plan: Run locally

Reviewers: khamidou, evan, juan

Reviewed By: juan

Differential Revision: https://phab.nylas.com/D3508

packages/local-sync/src/models/contact.js

@@ -22,7 +22,7 @@ module.exports = (sequelize, Sequelize) => {
     instanceMethods: {
       toJSON() {
         return {
-          id: `${this.publicId}`,
+          id: `${this.id}`,
           account_id: this.accountId,
           object: 'contact',
           email: this.email,