`wslc pull` behind a corporate proxy (HTTP_PROXY, HTTPS_PROXY, NO_PROXY)

**Is your feature request related to a problem? Please describe.**
It appears that WSLC doesn't provide a way to configure HTTP proxy settings for the `wslc` commands. So running commands such as `wslc pull` fails with error message. Error message example:

```
PS C:\hello> wslc pull hello-world
Get "https://registry-1.docker.io/v2/": dial tcp: lookup registry-1.docker.io on pi:53: read udp ip:11046->ip: i/o timeout
Error code: E_FAIL
```

**Describe the solution you'd like**
1. A documentation that explains how HTTP proxy settings can be configured for WSLC.
2. When possible/viable, automatically mirror HTTP proxy settings from Windows host OS.
3. Provide an option to configure proxy settings via WSLC settings.yaml (similar to Docker's `proxies` section in daemon.json).