Bug fix for init_args

[iguinn]

init_args inputs were only parsing strings. Added a test of init_args parsing and fixed bug. Also improved examples in documentation.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 63.75%. Comparing base (fcadf3f) to head (7beaf43).
⚠️ Report is 11 commits behind head on main.

Files with missing lines	Patch %	Lines
src/dspeed/processing_chain.py	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #185      +/-   ##
==========================================
- Coverage   63.77%   63.75%   -0.02%     
==========================================
  Files          61       61              
  Lines        4008     4009       +1     
==========================================
  Hits         2556     2556              
- Misses       1452     1453       +1     

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