use the same variable name for PackageId/PackageName on Core project

[joaoopereira]

We should use always the same variable name on core project:

cli/core/StartupModule.cs

Line 23 in df7956a

/// <param name="packageName">Package name used for INPMClient implementations</param>

vs

cli/core/Objects/ExecutionContext.cs

Line 50 in df7956a

public static string PackageId => (ServiceProvider.GetService<IVersionService>()!.PackageId) ?? "unknown";

IMO we should use PackageId