CA-343280: Extended proxy authentication.

[kc284]

No description provided.

[edwintorok]

There are some .Net classes for parsing/creating Http headers, could those be used instead of parsing the string manually? https://docs.microsoft.com/en-us/dotnet/api/system.net.http.headers?view=net-5.0
https://docs.microsoft.com/en-us/dotnet/api/system.net.webproxy.credentials?view=net-5.0 there is also a credentials property for webproxy, but it doesn't say what kind of auth it supports, it says it supports both basic and digest but doesn't specify what algorithm: https://docs.microsoft.com/en-us/dotnet/framework/network-programming/basic-and-digest-authentication