support sparse dataset

[ShawnShawnYou]

• support sparse dataset
• support sparse vector search #324

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

@@            Coverage Diff            @@
##           main     #325       +/-   ##
=========================================
+ Coverage      0   88.12%   +88.12%     
=========================================
  Files         0      145      +145     
  Lines         0     9337     +9337     
=========================================
+ Hits          0     8228     +8228     
- Misses        0     1109     +1109     

Flag	Coverage Δ
cpp	88.12% <100.00%> (?)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
include/vsag/dataset.h	100.00% <100.00%> (ø)
src/dataset_impl.h	100.00% <100.00%> (ø)
src/dataset_impl_test.cpp	100.00% <100.00%> (ø)

... and 142 files with indirect coverage changes