bazel does not honor https_proxy and no_proxy environment settings on windows

### Description of the problem / feature request:

If I set on windows environment variables for bazel regarding proxy, the `no_proxy` setting seems to be ignored or not working correctly (hard to find out).

### Feature requests: what underlying problem are you trying to solve with this feature?

I'm trying to use bazel with the following setup:

* External resources (like to download bazel rules) need to go through a corporate proxy. To do this I setup the proxy (with Powershell) like this:

`$env:https_proxy="http://my.cortporate.proxy:3128"`

This works correct and bazel seems to download some rules (after a fresh installation).

Now I have a rule like "`rules_jvm_external`" which is used to download project dependency like maven from an internal corporate repository. This repository is internal and all requests to this should NOT go through the proxy. So I tried the following for my example domain https://my.corporate.domain/nexus with Powershell:

`$env:no_proxy=".corporate.domain,*.corporate.domain`

But both are not working. Bazel only starts to download my maven dependencies after remove the `https_proxy` variable from the environment.

### Bugs: what's the simplest, easiest way to reproduce this bug? Please provide a minimal example if possible.

Setup an internal repository to download maven dependencies. Using a proxy to download all the rest from the internet.

setup the https_proxy, http_proxy and no_proxy environment variables ... now the download from the "`no_poxy`" repository does not work.

You can also test it like this: setup `https_poxy` to something (where you know it does not work) and setup `no_proxy` to exclude for example `.gihub.com` ... then I would expect that bazel can download from github.com ... but it doesn't.

### What operating system are you running Bazel on?

Windows 10

### What's the output of `bazel info release`?

release 1.0.0

### Have you found anything relevant by searching the web?

Not really

Reproduce on Windows 10 with Bazel 1.0.0 by setting https_proxy, http_proxy, and no_proxy, then attempting to fetch an internal Maven repository or github.com. Trace the proxy handling used by rules_jvm_external and verify that excluded hosts bypass the proxy while external resources still use it.

Written by the indexing model from the issue text.