Strengthen variable bound constraints using mixed-integer rounding

[fwesselm]

• Use MIR to strengthen variable bound constraints derived in HPresolve::extractVarBounds.
• HiGHS performance is only slightly affected (ratios of shifted geometric means of running times and numbers of branching nodes are very close to 1.0).

[Opt-Mucca]

Happy with the change!

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 80.65%. Comparing base (a45f555) to head (c1a8ebe).
⚠️ Report is 13 commits behind head on latest.

Additional details and impacted files

@@           Coverage Diff           @@
##           latest    #2907   +/-   ##
=======================================
  Coverage   80.65%   80.65%           
=======================================
  Files         347      347           
  Lines       86672    86690   +18     
=======================================
+ Hits        69902    69920   +18     
  Misses      16770    16770           

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