more Dataset skeleton funcs: get_dataset_columns and get_plottable_columns

src/Dataset.py

@@ -12,3 +12,9 @@ class Dataset:
 
     def draw_histogram(self):
         raise NotImplementedError
+
+    def get_dataset_columns(self) -> list:
+        raise NotImplementedError
+
+    def get_plottable_columns(self) -> list:
+        raise NotImplementedError