Python: Remove manual magic entirely

This was causing issues with imports with many "dots" in the name.

Previously, the test added in this commit would not have the desired
result for the `check` call.

python/ql/lib/semmle/python/dataflow/new/internal/ImportResolution.qll

@@ -231,7 +231,6 @@ module ImportResolution {
     // Reading an attribute on a module may return a submodule (or subpackage).
     exists(DataFlow::AttrRead ar, Module p, string attr_name |
       ar.accesses(getModuleReference(p), attr_name) and
-      attr_name = any(Module m0).getFile().getStem() and
       result = ar
     |
       isPreferredModuleForName(m.getFile(), p.getPackageName() + "." + attr_name + ["", ".__init__"])

python/ql/test/experimental/import-resolution/main.py

@@ -69,6 +69,11 @@ check("aliased_subpackage.subpackage_attr", aliased_subpackage.subpackage_attr,
 import package.subpackage #$ imports=package.__init__ as=package
 check("package.package_attr", package.package_attr, "package_attr", globals()) #$ prints=package_attr
 
+# Deep imports
+import package.subpackage.submodule #$ imports=package.__init__ as=package
+check("package.subpackage.submodule.submodule_attr", package.subpackage.submodule.submodule_attr, "submodule_attr", globals()) #$ prints=submodule_attr
+
+
 if sys.version_info[0] == 3:
     # Importing from a namespace module.
     from namespace_package.namespace_module import namespace_module_attr