moved frontend function check_not_nan to tools

src/submissions/tools/__init__.py

@@ -0,0 +1,13 @@
+import numpy as np
+import logging
+
+logger = logging.getLogger(f"submissions.{__name__}")
+
+def check_not_nan(cell_contents) -> bool:
+    try:
+        return not np.isnan(cell_contents)
+    except TypeError:
+        return True
+    except Exception as e:
+        logger.debug(f"Check encounteded unknown error: {type(e).__name__} - {e}")
+        return False