Merge #3296

3296: vscode: bump TypeScript version r=matklad a=Veetaha

There is a new [`type-only` import and export feature](https://www.typescriptlang.org/docs/handbook/release-notes/typescript-3-8.html#-type-only-imports-and-export), but let's keep our codebase as simple as it is now.
Also, top-level await :tada:, though with a caveat ))

![image](https://user-images.githubusercontent.com/36276403/75185341-93629b00-574e-11ea-8d5c-4a4293f140f7.png)

Co-authored-by: Veetaha <gerzoh1@gmail.com>