add test verifying go list of dependencies on cmd/gnoland doesn't contain tests/stdlibs

[kristovatlas]

Description

We have methods on std that are intended to be used for testing, but theoretically they could be misused from VM normal execution, e.g. std.TestSetRealm.

These methods are not currently compiled into the gnoland binary, but to avoid accidental regression in the future, we can add a test to ensure that a go list of dependencies on cmd/gnoland doesn't contain tests/stdlibs.

Suggestion from @ajnavarro and @thehowl.