Fix and test solvers for non-square operators

[ChrisRackauckas]

Fixes #414

[codecov]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (30ff6eb) 65.54% compared to head (40743e1) 66.06%.

Files	Patch %	Lines
src/iterative_wrappers.jl	90.90%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #454      +/-   ##
==========================================
+ Coverage   65.54%   66.06%   +0.52%     
==========================================
  Files          27       27              
  Lines        2104     2122      +18     
==========================================
+ Hits         1379     1402      +23     
+ Misses        725      720       -5     

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