Move OptimizationStats to SciMLBase

[Vaibhavdixit02]

Checklist

• Appropriate tests were added
• Any code changes were done in a way that does not break public API
• All documentation related to code changes were updated
• The new code follows the
  contributor guidelines, in particular the SciML Style Guide and
  COLPRAC.
• Any new documentation only uses public API

Additional context

Add any other context about the problem here.

[ChrisRackauckas]

As a cleanup, @avik-pal we should start removing this wherever we see it

[ChrisRackauckas]

Test failures 😓

[codecov]

Codecov Report

Attention: 15 lines in your changes are missing coverage. Please review.

Comparison is base (bc92540) 30.43% compared to head (0f8bb02) 30.40%.
Report is 13 commits behind head on master.

Files	Patch %	Lines
src/problems/optimization_problems.jl	47.61%	11 Missing ⚠️
src/solutions/optimization_solutions.jl	0.00%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #600      +/-   ##
==========================================
- Coverage   30.43%   30.40%   -0.04%     
==========================================
  Files          53       54       +1     
  Lines        4045     4049       +4     
==========================================
  Hits         1231     1231              
- Misses       2814     2818       +4     

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