Add support for query a different domain/forest

[leechristensen]

Right now PSPKIAudit only enumerates the forest of the currently authenticated user. This is fine if there's only one AD forest since AD CS configuration is defined Forest-wide.

If there's more than one Forest in the environment, though, the only way to enumerate the misconfigurations is by logging on as a user in the other Forest and then running PSPKIAudit. It'd be nice if PSPKIAudit could take a domain as a parameter and enumerate the misconfigurations in a remote domain.