Add MemoryAllocator and CAllocator

[jslee02]

Initial work for adding custom memory allocator:

• Add MemoryAllocator that is a base class for custom memory allocators
• Add CAllocator that is a simple wrapper of std::malloc and std::free

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Before creating a pull request

• Document new methods and classes
• Format new code files using ClangFormat by running make format
• Build with -DDART_TREAT_WARNINGS_AS_ERRORS=ON and resolve build warnings

Before merging a pull request

• Set version target by selecting a milestone on the right side
• Summarize this change in CHANGELOG.md
• Add unit test(s) for this change

[codecov]

Codecov Report

Merging #1636 (7a5a8b1) into main (627f71e) will increase coverage by 0.02%.
The diff coverage is 72.09%.

❗ Current head 7a5a8b1 differs from pull request most recent head fc60b2f. Consider uploading reports for the commit fc60b2f to get more accurate results

@@            Coverage Diff             @@
##             main    #1636      +/-   ##
==========================================
+ Coverage   58.93%   58.95%   +0.02%     
==========================================
  Files         477      483       +6     
  Lines       40166    40252      +86     
==========================================
+ Hits        23670    23729      +59     
- Misses      16496    16523      +27     

Impacted Files	Coverage Δ
dart/common/CAllocator.hpp	0.00% <0.00%> (ø)
dart/common/MemoryAllocator.cpp	0.00% <0.00%> (ø)
dart/common/CAllocator.cpp	72.09% <72.09%> (ø)
dart/common/MemoryAllocator.hpp	100.00% <100.00%> (ø)
dart/common/detail/Logging-impl.hpp	100.00% <100.00%> (ø)
python/dartpy/common/Logging.cpp	100.00% <100.00%> (ø)
python/dartpy/common/module.cpp	100.00% <100.00%> (ø)
dart/dynamics/Skeleton.cpp	67.74% <0.00%> (-0.17%)	⬇️