This PR adds es2015 lib to the `tsconfig.json` of the test project so
that `Promise` could be used. Note this only affects diagnostics in the
IDE. The tsconfig in Language Service Mock Host is the actual config
values used, and it already has es2015 lib.
- Other minor cleanup: Rename imports in `main.ts`.
- Add more cases to `parsing-cases.ts`, which are tested in later PRs
PR Close#33157
Language service uses a canonical "Tour of Heroes" project to test
various features, but the files are all contained in test_data.ts which
is hard to read and often contains errors that are difficult to catch
without proper IDE syntax highlighting. The directory structure is also
not clear from first glance.
This PR refactors the test project into standalone files in the proper
format.
Next up:
[ ] Update the interface of MockTypeScript to only accept scriptNames.
[ ] Remove test_data.ts
PR Close#32653
Keen Yee Liau