feat(return-await): require return await in try/catch blocks

Returned promises will not be caught in an async function try/catch,
so this results in more consistent stack traces.

packages/typescript/index.js

@@ -2,6 +2,7 @@ module.exports = {
   extends: ['plugin:@typescript-eslint/recommended'],
   plugins: ['@typescript-eslint'],
   rules: {
+    '@typescript-eslint/return-await': 'error',
     '@typescript-eslint/explicit-function-return-type': 1,
     '@typescript-eslint/no-var-requires': 'off',
     '@typescript-eslint/interface-name-prefix': 'off',