socks proxy doesn't work

### What You Are Seeing?
proxy scheme not support warning

### What is Expected?
choco support socks5 proxy

see https://chocolatey.org/docs/proxy-settings-for-chocolatey#what-to-do-if-my-proxy-is-socks

### How Did You Get This To Happen? (Steps to Reproduce)
`choco config set proxy socks5://localhost:7890`
choch search python

I also tried `socks5h` and `socks`.

### Output Log
```
choco search python
Chocolatey v0.10.15
2 validations performed. 1 success(es), 1 warning(s), and 0 error(s).

Validation Warnings:
- A pending system reboot request has been detected, however, this is
being ignored due to the current command being used 'search'.
It is recommended that you reboot at your earliest convenience.

[NuGet] Not able to contact source 'https://chocolatey.org/api/v2/'. Error was The ServicePointManager does not support proxies with the socks5 scheme.
[NuGet] Not able to contact source 'https://chocolatey.org/api/v2/'. Error was The ServicePointManager does not support proxies with the socks5 scheme.
0 packages found.
```

Start by reproducing `choco config set proxy socks5://localhost:7890` followed by `choco search python`, then trace the proxy configuration and source-request handling that produces the ServicePointManager warning. Done means Chocolatey can use the configured SOCKS5 proxy for the search request without the unsupported-scheme warning.

Written by the indexing model from the issue text.