Apply documented defaults to format options

[JordanNoone]

Apply the documented defaults when OBJ, PLY, STL, and glTF option fields are omitted. The generated OpenAPI schema no longer marks those fields as required.

Closes #1300.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
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Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1353   +/-   ##
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  Coverage        ?   36.12%           
=======================================
  Files           ?       36           
  Lines           ?     1813           
  Branches        ?        0           
=======================================
  Hits            ?      655           
  Misses          ?     1158           
  Partials        ?        0           

Flag	Coverage Δ
unittests	36.12% <100.00%> (?)

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