Issue Type: Feature Request

Hello! Many Windows Apps honor metered connection and ask if they can download stuff in the background - VSCode went all in and just started downloading stuff it was missing. At the time it was fine for me as I'm on nearly unlimited metered plan, but for others it might be not so pleasant experience.

VS Code version: Code 1.34.0 (a622c65, 2019-05-15T21:59:37.030Z)
OS version: Windows_NT x64 10.0.18362