We should have a clear separation of system-wide and user environments similar to [`EnvironmentVariableTarget`](https://docs.microsoft.com/en-us/dotnet/api/system.environment.getenvironmentvariable?view=netcore-3.1#System_Environment_GetEnvironmentVariable_System_String_System_EnvironmentVariableTarget_). By default, both types of environments should be returned, and `CondaEnvironment` should be able to tell the type to distinguish between them.