Allow API keys to be used in NuGetPackageSourceCredentials env variables

[ViliusS]

NuGet Product(s) Involved

NuGet.exe, NuGet SDK

The Elevator Pitch

NuGetPackageSourceCredentials_{key} environment variables are a great way to pass source credentials in CI/CD pipelines, however it only accepts Username and Password currently. If NuGet repository is configured to require MFA or SSO this fails. This also fails when user password rotation is in place. It would be more appropriate and secure to allow API keys in these variables.

Additional Context and Details

No response

[Nigusu-Allehu]

We appreciate the suggestions!
To better understand the motivation and evaluate potential alternatives:
Which source are you trying to use this with, and in what scenario would you apply it?