Implement dotnet nuget config command

[heng-liu]

Implement the equivalent dotnet command of nuget config command

[erdembayar]

@heng-liu @zkat @kartheekp-ms @aortiz-msft
Do you have spec for this one?

[zkat]

No. We'll need one and will have to run it by Kathleen, too.

[nkolev92]

Closing this in favor of #7133, which is a community ask with a lot more upvotes