Respect VS Code's built-in proxy settings

[EhabY]

VS Code provides a few settings for proxy configuration:

• http.noProxy
• http.proxy
• http.proxyAuthorization
• http.proxyStrictSSL
• Possible others

We should adhere and respect those settings while falling back on environment variables if it applies. See the following for more info coder/coder#21666 (comment)