check outer package dependencies in subpackage_dependencies_test

[sigmundch]

No description provided.

[jensjoha]

Could you provide more details?

[sigmundch]

subpackage_dependencies_test was written to ensure that we didn't pull in unnecessary dependencies in package:front_end. We talked about two kind of dependencies:

• internal dependencies between folders: we currently test these and we added them because package:front_end includes code that is needed by analyzer, but not by other backends of the front_end
• external dependencies: we have no checks for these, but the goal was to check that we carefully review whenever we add a new dependency, especially when we import another package from the fasta directory, indicating that this will be a dependency for all users of the front-end.