Fix cppcheck performance passedByValue warnings

[MaximSmolskiy]

No description provided.

[codecov]

Codecov Report

Attention: Patch coverage is 55.55556% with 8 lines in your changes missing coverage. Please review.

Please upload report for BASE (check-2181@4c783d9). Learn more about missing BASE report.

Files with missing lines	Patch %	Lines
src/util/HighsUtils.cpp	40.00%	3 Missing ⚠️
src/io/HighsIO.cpp	0.00%	2 Missing ⚠️
src/lp_data/HighsDebug.cpp	0.00%	2 Missing ⚠️
src/lp_data/HighsIis.cpp	0.00%	1 Missing ⚠️

Additional details and impacted files

@@              Coverage Diff              @@
##             check-2181    #2181   +/-   ##
=============================================
  Coverage              ?   78.81%           
=============================================
  Files                 ?      345           
  Lines                 ?    83174           
  Branches              ?        0           
=============================================
  Hits                  ?    65551           
  Misses                ?    17623           
  Partials              ?        0           

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[jajhall]

I understand your motivation for making these changes. Passing strings by value is of no great importance, but I see that there are a few vectors that you've picked up on.

I've merged it into a branch rather than latest so I can study your changes and fix the formatting