Moving the DatabaseLoader support into Microsoft.ML.Data

[tannergooding]

This resolves #4323

[tannergooding]

CC. @eerhardt, @CESARDELATORRE

[codecov]

Codecov Report

Merging #4342 into master will decrease coverage by 0.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #4342      +/-   ##
==========================================
- Coverage   74.56%   74.55%   -0.02%     
==========================================
  Files         879      879              
  Lines      154524   154524              
  Branches    16883    16883              
==========================================
- Hits       115218   115198      -20     
- Misses      34554    34579      +25     
+ Partials     4752     4747       -5

Flag	Coverage Δ
#Debug	74.55% <ø> (-0.02%)	⬇️
#production	70.12% <ø> (-0.02%)	⬇️
#test	89.54% <ø> (ø)	⬆️

Impacted Files	Coverage Δ
src/Microsoft.ML.Data/Data/SchemaDefinition.cs	70.55% <ø> (ø)	⬆️
...ata/DataLoadSave/Database/DatabaseLoaderCatalog.cs	100% <ø> (ø)
...t.ML.Data/DataLoadSave/Text/LoadColumnAttribute.cs	100% <ø> (ø)	⬆️
...a/DataLoadSave/Database/LoadColumnNameAttribute.cs	100% <ø> (ø)
...ft.ML.Data/DataLoadSave/Database/DatabaseLoader.cs	52.39% <ø> (ø)
...Data/DataLoadSave/Database/DatabaseLoaderCursor.cs	22.62% <ø> (ø)
...ft.ML.Data/DataLoadSave/Database/DatabaseSource.cs	100% <ø> (ø)
...soft.ML.Data/DataLoadSave/Database/DbExtensions.cs	18.51% <ø> (ø)
src/Microsoft.ML.AutoML/Sweepers/ISweeper.cs	59.49% <0%> (-7.6%)	⬇️
src/Microsoft.ML.AutoML/Sweepers/Parameters.cs	77.96% <0%> (-5.09%)	⬇️
... and 5 more

[eerhardt]

I believe we can remove this file now:

https://github.com/dotnet/machinelearning/blob/master/src/Microsoft.ML.Experimental/Properties/AssemblyInfo.cs

It was only added for the DatabaseLoader change.

Also, I believe we can revert remove this line as well:

machinelearning/src/Microsoft.ML.Core/Properties/AssemblyInfo.cs

Line 25 in 461b7d3

[assembly: InternalsVisibleTo(assemblyName: "Microsoft.ML.Experimental" + PublicKey.Value)]

Basically, we can undo the extra workarounds in #4035.

It looks like there are 2 workarounds that can be undone from #4091. (Adding 2 [BestFriend] attributes.)

[eerhardt]

This looks good. We should undo the extraneous changes we made along the way now that this code is in the core package. Once those are reverted, this should be merged.