Add E2E tests for using sources that requires Certificate authentication

## Is Your Feature Request Related To A Problem? Please describe.

In the Chocolatey CLI codebase we have code that makes it possible to use a Certificate and Certificate password when authenticating with Chocolatey feed sources.
At the moment we do not have any tests for this functionality, and AFAIK no way to test whether this functionality works as intended.

## Describe The Solution. Why is it needed?

We need to look into how to implement E2E tests when authenticating to Chocolatey feed sources that makes use of certificate authentication, both if they are configured as global sources or passed in during install/upgrade/list/info commands.

## Additional Context.

It is possible that this functionality do not exist in later version of the NuGet codebase, meaning once we update the references used, we do not have this functionality anymore.
This also needs to be looked into, and if determined if we will not support the functionality in the future it will need to be deprecated instead of adding tests for this.

## Related Issues

N/A.

Start by locating the Chocolatey CLI code that handles certificate and certificate-password authentication and the existing E2E test setup. Check whether the referenced NuGet functionality still exists, then determine how global sources and install, upgrade, list, and info commands can be covered; done means supported behavior is tested or the feature is formally deprecated.

Written by the indexing model from the issue text.