Test TypeScript program and module resolution cache

Test "custom tsc" with watch mode and ts.SourceFile cache. It emulates running 3 builds on the following project structore:

/a.ts (imports /module/b.d.ts)
/module/b.d.ts
  1. Successful build
  2. Delete file /module/b.d.ts. Build fails with error "TS2307: Cannot find module"
  3. Restore file /module/b.d.ts. Build still fails, but I would expect it to succeed again

To reproduce:

$ npm ci
$ node index.js