[KNITRO] Add warm start support

[eminyouskn]

Fixes # .

Summary/Motivation:

This PR implements the warm-start procedure for the KNITRO solver.

Changes proposed in this PR:

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.93%. Comparing base (52a29ae) to head (4eb7f15).
⚠️ Report is 274 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3833      +/-   ##
==========================================
- Coverage   89.94%   89.93%   -0.01%     
==========================================
  Files         902      902              
  Lines      106354   106369      +15     
==========================================
+ Hits        95655    95664       +9     
- Misses      10699    10705       +6     

Flag	Coverage Δ
builders	29.20% <20.00%> (+<0.01%)	⬆️
default	86.23% <100.00%> (?)
expensive	35.65% <20.00%> (?)
linux	87.37% <20.00%> (-2.05%)	⬇️
linux_other	87.37% <20.00%> (-0.01%)	⬇️
oldsolvers	28.11% <20.00%> (+<0.01%)	⬆️
osx	82.70% <20.00%> (-0.01%)	⬇️
win	85.79% <20.00%> (-0.03%)	⬇️
win_other	85.79% <20.00%> (-0.03%)	⬇️

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[michaelbynum]

This PR looks great, but it raised a broader design discussion for solver configs (see #3933 ). We are trying to figure out how to have common config options among subsets of solvers. For this PR, I think we just rename use_start to be knitro_use_warmstart so that it is clear that this option is specific to knitro. With that change, I think this will be ready to go.