Added a new selector MinBoundaryHighDegreeSelector

[ArrogantGao]

This selector has two new field to handle high degree points more flexibly.

[codecov]

Codecov Report

Attention: Patch coverage is 95.23810% with 1 line in your changes missing coverage. Please review.

Project coverage is 90.78%. Comparing base (c574a40) to head (d58f750).
Report is 9 commits behind head on main.

Files with missing lines	Patch %	Lines
lib/OptimalBranchingMIS/src/selector.jl	94.73%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #20      +/-   ##
==========================================
+ Coverage   90.25%   90.78%   +0.52%     
==========================================
  Files          18       18              
  Lines         780      803      +23     
==========================================
+ Hits          704      729      +25     
+ Misses         76       74       -2     

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