Implement a Base.show for OptimizationStats

[nathanaelbosch]

DEStats are nicely presented in the REPL. This PR implements the same functionality for OptimizationStats.

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

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 7 lines in your changes are missing coverage. Please review.

Project coverage is 38.43%. Comparing base (9cd4382) to head (4ba2869).

Files	Patch %	Lines
src/solutions/optimization_solutions.jl	0.00%	7 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #652      +/-   ##
==========================================
- Coverage   38.49%   38.43%   -0.07%     
==========================================
  Files          55       55              
  Lines        4291     4298       +7     
==========================================
  Hits         1652     1652              
- Misses       2639     2646       +7     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.