Every network access should be logged and ideally display its progress

This is motivated by issues like https://github.com/commercialhaskell/stack/issues/2618 and instances where `stack` mysteriously hangs because the `snapshots.json` file cannot be downloaded.

For (`git`) subprocesses the necessary machinery [is already in place](https://github.com/commercialhaskell/stack/blob/master/src/Stack/PackageIndex.hs#L265-L266), it only needs to be applied where needed, maybe with a little wrapper.

For direct network access [`Stack.Setup.chattyDownload`](https://github.com/commercialhaskell/stack/blob/7a54085361260a469815b9aa408264bee4cd68e4/src/Stack/Setup.hs#L1387) could be reused in a slightly generalized form. If that turns out to be too obnoxious for some usecases (like downloading the `snapshots.json` file), a short notice like `Downloading XYZ...` could suffice.