Adding support for MurmurHash KeyDataTypes

[Lynx1820]

ML.NET's behavior is to map zero input values to zero, instead of hashes.

• Adding that behavior to the onnx export and a test.

TODO: rebase once other murmurhash PR are merged

[codecov]

Codecov Report

Merging #5138 into master will increase coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #5138      +/-   ##
==========================================
+ Coverage   75.66%   75.68%   +0.01%     
==========================================
  Files         990      990              
  Lines      179815   179867      +52     
  Branches    19342    19346       +4     
==========================================
+ Hits       136061   136134      +73     
+ Misses      38482    38464      -18     
+ Partials     5272     5269       -3     

Flag	Coverage Δ
#Debug	75.68% <100.00%> (+0.01%)	⬆️
#production	71.57% <100.00%> (+0.01%)	⬆️
#test	88.93% <100.00%> (+<0.01%)	⬆️

Impacted Files	Coverage Δ
src/Microsoft.ML.Data/Transforms/Hashing.cs	82.16% <100.00%> (+0.70%)	⬆️
test/Microsoft.ML.Tests/OnnxConversionTest.cs	99.45% <100.00%> (+0.01%)	⬆️
src/Microsoft.ML.Featurizers/CategoricalImputer.cs	74.73% <0.00%> (-0.27%)	⬇️
...L.AutoML/TrainerExtensions/TrainerExtensionUtil.cs	86.89% <0.00%> (+1.74%)	⬆️
...rosoft.ML.AutoML/ColumnInference/TextFileSample.cs	62.91% <0.00%> (+3.31%)	⬆️
...c/Microsoft.ML.FastTree/Utils/ThreadTaskManager.cs	100.00% <0.00%> (+20.51%)	⬆️

[harishsk]

            }

What other datatype are we not supporting? Can we assert here instead?

---

Refers to: src/Microsoft.ML.Data/Transforms/Hashing.cs:1162 in 21ad377. [](commit_id = 21ad377, deletion_comment = False)

[Lynx1820]

            }

What other datatype are we not supporting? Can we assert here instead?

Refers to: src/Microsoft.ML.Data/Transforms/Hashing.cs:1162 in 21ad377. [](commit_id = 21ad377, deletion_comment = False)

All numeric types are now supported.

[harishsk]