Get Number of Contact Pairs

[srwopschall]

Adding API functions to return the number of contact pairs per rank and total pairs across all ranks. This will help catch bugs/changes in the computational geometry filtering and cg algorithm in general.

This routine is host callable meant for diagnostics/metrics.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 0% with 12 lines in your changes missing coverage. Please review.
✅ Project coverage is 90.61%. Comparing base (aa7679e) to head (7ee9c69).

Files with missing lines	Patch %	Lines
src/tribol/interface/tribol.cpp	0.00%	12 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #165      +/-   ##
===========================================
- Coverage    90.67%   90.61%   -0.06%     
===========================================
  Files          101      101              
  Lines        19234    19248      +14     
===========================================
+ Hits         17440    17442       +2     
- Misses        1794     1806      +12     

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[ebchin]

Add a warning re: ghost elements being counted multiple times.