Fix problem with rollup-plugin-ts and TS @ v5

[Chris Krycho]

Currently, the build reports this for TS v5.0.0 builds:

> tracked-built-ins@2.0.1 prepublishOnly /Users/ckrycho/dev/tracked-tools/tracked-built-ins/addon
> rollup --config


 → dist...
(!) Unresolved dependencies
https://rollupjs.org/guide/en/#warning-treating-module-as-external-dependency
@babel/runtime/helpers/esm/classPrivateFieldGet (imported by src/-private/object.js, src/-private/array.ts)
(!) Generated an empty chunk
object.d
[!] (plugin Typescript) TS2792: Cannot find module 'ember-tracked-storage-polyfill'. Did you mean to set the 'moduleResolution' option to 'nodenext', or to add aliases to the 'paths' option?
src/-private/map.ts (6:8)

6 } from 'ember-tracked-storage-polyfill';
         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


 ELIFECYCLE  Command failed with exit code 1.

I have yet to do any investigation, so it's possible this is a bug in any of the following places:

• the build for ember-tracked-storage-polyfill
• our consumption of ember-tracked-storage-polyfill in this package
• rollup-plugin-ts
• maaaaaybe TypeScript itself