Update gen commands (SYN-9906)

[mikemoritz]

Per the ticket, some gen commands were removed, and all gen library functions were marked private.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 96.65%. Comparing base (1f81dfd) to head (ebe14a1).
⚠️ Report is 1 commits behind head on synapse-3xx.

Additional details and impacted files

@@               Coverage Diff               @@
##           synapse-3xx    #4637      +/-   ##
===============================================
- Coverage        96.68%   96.65%   -0.03%     
===============================================
  Files              252      252              
  Lines            60723    60723              
===============================================
- Hits             58710    58694      -16     
- Misses            2013     2029      +16     

Flag	Coverage Δ
linux	96.65% <100.00%> (-0.03%)	⬇️

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