chore: Move to Typescript (#2783)

This PR moves the entire project to Typescript. Due to the ~1000 ignores this will lead to a messy codebase for a while, but the churn is worth it – all of those ignore comments are places that were never type-safe previously.

closes #1282

server/migrations/20170904202454-allow-null-username.js

@@ -1,13 +1,12 @@
 module.exports = {
   up: async (queryInterface, Sequelize) => {
-    await queryInterface.changeColumn('users', 'username', {
+    await queryInterface.changeColumn("users", "username", {
       type: Sequelize.STRING,
       allowNull: true,
     });
   },
-
   down: async (queryInterface, Sequelize) => {
-    await queryInterface.changeColumn('users', 'username', {
+    await queryInterface.changeColumn("users", "username", {
       type: Sequelize.STRING,
       allowNull: false,
     });