Make module/dependency selection configurable

[lefou]

My main use case is to exclude some test modules, that are required to ensure backward-compatibility. That way, these test need to run against older app versions which are known to contain vulnerabilies. Due to that, I seen various reports which don't really originate in the project itself.

My suggestion is to just add a selector for the dependency targets. Mill's nice query syntax allows fine grained selection. E.g. to check all runtime dependencies of non-test modules, we could accept __:^TestModule.resolvedRunIvyDeps.