Move NOT_DATA to its own module

[liamhuber]

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👈 Launch a binder notebook on branch pyiron/pyiron_workflow/data

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.37%. Comparing base (fe9d937) to head (1531869).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #746   +/-   ##
=======================================
  Coverage   93.37%   93.37%           
=======================================
  Files          34       35    +1     
  Lines        3606     3610    +4     
=======================================
+ Hits         3367     3371    +4     
  Misses        239      239           

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