fix: avoid using implicit new operator to manage memory

[SYaoJun]

Reason for this PR

include common functions under graphar namespace and replace implicit memory with vector and smart pointer.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 80.59%. Comparing base (b21da29) to head (785baae).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main     #915      +/-   ##
============================================
- Coverage     80.60%   80.59%   -0.01%     
  Complexity      615      615              
============================================
  Files            94       94              
  Lines         10709    10706       -3     
  Branches       1055     1054       -1     
============================================
- Hits           8632     8629       -3     
  Misses         1837     1837              
  Partials        240      240              

Flag	Coverage Δ
cpp	70.88% <100.00%> (-0.02%)	⬇️

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