Issue #6606 - Add sample variance and standard deviation to NormalizeMeanVariance

[tearlant]

Associated issue: https://github.com/dotnet/machinelearning/issues/6606

Adding a flag so that NormalizeMeanVariance can use the sample variance/standard deviation instead of the population variance/standard deviation

[tearlant]

@dotnet-policy-service agree

[codecov[bot]]

Codecov Report

Merging #6879 (371e61d) into main (796cb35) will decrease coverage by 0.01%. The diff coverage is 55.00%.

@@            Coverage Diff             @@
##             main    #6879      +/-   ##
==========================================
- Coverage   69.40%   69.40%   -0.01%     
==========================================
  Files        1238     1238              
  Lines      249462   249482      +20     
  Branches    25522    25534      +12     
==========================================
+ Hits       173139   173148       +9     
- Misses      69578    69707     +129     
+ Partials     6745     6627     -118     

Flag	Coverage Δ
Debug	69.40% <55.00%> (-0.01%)	:arrow_down:
production	63.92% <55.00%> (-0.01%)	:arrow_down:
test	88.90% <ø> (ø)

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

Files	Coverage Δ
src/Microsoft.ML.Data/Transforms/Normalizer.cs	86.28% <100.00%> (+0.06%)	:arrow_up:
...Microsoft.ML.Data/Transforms/NormalizeColumnSng.cs	76.47% <57.89%> (-0.42%)	:arrow_down:
...Microsoft.ML.Data/Transforms/NormalizeColumnDbl.cs	69.35% <47.36%> (-0.40%)	:arrow_down:

... and 10 files with indirect coverage changes