fix(core): Remove old directory state logic

- Remove code forcing the exclusion of `.` directories by default, the
  new default exclusion filters do this by default
- Change default state code to always return a value

core/tests/directories_test.py

@@ -326,6 +326,7 @@ def test_default_path_state_override(tmpdir):
         def _default_state_for_path(self, path):
             if "foobar" in path.parts:
                 return DirectoryState.EXCLUDED
+            return DirectoryState.NORMAL
 
     d = MyDirectories()
     p1 = Path(str(tmpdir))