Reorganize dataframe files

[asmirnov82]

Code is not changed. This PR only reorganizes files (moves all PrimitiveDataFrameColumns and internal util under separate folders, split unit tests into separate files based on the area being tested). The aim of this PR is to make futher development easier.

[asmirnov82]

@michaelgsharp could you please take a look and approve while Jake is on vacation? There isn't any changes in the code. This PR reorganizes files inside dataframe project to simplify project structure and make it easier to change unit tests (and track these changes) in future development

[codecov[bot]]

Codecov Report

Merging #6872 (23aa3ae) into main (796cb35) will increase coverage by 0.06%. Report is 9 commits behind head on main. The diff coverage is 99.00%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #6872 +/- ## ========================================== + Coverage 69.40% 69.46% +0.06% ========================================== Files 1238 1249 +11 Lines 249462 250702 +1240 Branches 25522 25875 +353 ========================================== + Hits 173139 174154 +1015 - Misses 69578 69803 +225 Partials 6745 6745 ``` | [Flag](https://app.codecov.io/gh/dotnet/machinelearning/pull/6872/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dotnet) | Coverage Δ | | |---|---|---| | [Debug](https://app.codecov.io/gh/dotnet/machinelearning/pull/6872/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dotnet) | `69.46% <99.00%> (+0.06%)` | :arrow_up: | | [production](https://app.codecov.io/gh/dotnet/machinelearning/pull/6872/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dotnet) | `63.96% <ø> (+0.03%)` | :arrow_up: | | [test](https://app.codecov.io/gh/dotnet/machinelearning/pull/6872/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dotnet) | `88.95% <99.00%> (+0.05%)` | :arrow_up: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dotnet#carryforward-flags-in-the-pull-request-comment) to find out more. | [Files](https://app.codecov.io/gh/dotnet/machinelearning/pull/6872?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dotnet) | Coverage Δ | | |---|---|---| | [...sis/DataFrameColumns/ArrowStringDataFrameColumn.cs](https://app.codecov.io/gh/dotnet/machinelearning/pull/6872?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dotnet#diff-c3JjL01pY3Jvc29mdC5EYXRhLkFuYWx5c2lzL0RhdGFGcmFtZUNvbHVtbnMvQXJyb3dTdHJpbmdEYXRhRnJhbWVDb2x1bW4uY3M=) | `63.54% <ø> (ø)` | | | [...rimitiveDataFrameColumns/BooleanDataFrameColumn.cs](https://app.codecov.io/gh/dotnet/machinelearning/pull/6872?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dotnet#diff-c3JjL01pY3Jvc29mdC5EYXRhLkFuYWx5c2lzL0RhdGFGcmFtZUNvbHVtbnMvUHJpbWl0aXZlRGF0YUZyYW1lQ29sdW1ucy9Cb29sZWFuRGF0YUZyYW1lQ29sdW1uLmNz) | `100.00% <ø> (ø)` | | | [...s/PrimitiveDataFrameColumns/ByteDataFrameColumn.cs](https://app.codecov.io/gh/dotnet/machinelearning/pull/6872?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dotnet#diff-c3JjL01pY3Jvc29mdC5EYXRhLkFuYWx5c2lzL0RhdGFGcmFtZUNvbHVtbnMvUHJpbWl0aXZlRGF0YUZyYW1lQ29sdW1ucy9CeXRlRGF0YUZyYW1lQ29sdW1uLmNz) | `100.00% <ø> (ø)` | | | [...s/PrimitiveDataFrameColumns/CharDataFrameColumn.cs](https://app.codecov.io/gh/dotnet/machinelearning/pull/6872?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dotnet#diff-c3JjL01pY3Jvc29mdC5EYXRhLkFuYWx5c2lzL0RhdGFGcmFtZUNvbHVtbnMvUHJpbWl0aXZlRGF0YUZyYW1lQ29sdW1ucy9DaGFyRGF0YUZyYW1lQ29sdW1uLmNz) | `90.90% <ø> (ø)` | | | [...imitiveDataFrameColumns/DateTimeDataFrameColumn.cs](https://app.codecov.io/gh/dotnet/machinelearning/pull/6872?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dotnet#diff-c3JjL01pY3Jvc29mdC5EYXRhLkFuYWx5c2lzL0RhdGFGcmFtZUNvbHVtbnMvUHJpbWl0aXZlRGF0YUZyYW1lQ29sdW1ucy9EYXRlVGltZURhdGFGcmFtZUNvbHVtbi5jcw==) | `90.90% <ø> (ø)` | | | [...rimitiveDataFrameColumns/DecimalDataFrameColumn.cs](https://app.codecov.io/gh/dotnet/machinelearning/pull/6872?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dotnet#diff-c3JjL01pY3Jvc29mdC5EYXRhLkFuYWx5c2lzL0RhdGFGcmFtZUNvbHVtbnMvUHJpbWl0aXZlRGF0YUZyYW1lQ29sdW1ucy9EZWNpbWFsRGF0YUZyYW1lQ29sdW1uLmNz) | `90.90% <ø> (ø)` | | | [...PrimitiveDataFrameColumns/DoubleDataFrameColumn.cs](https://app.codecov.io/gh/dotnet/machinelearning/pull/6872?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dotnet#diff-c3JjL01pY3Jvc29mdC5EYXRhLkFuYWx5c2lzL0RhdGFGcmFtZUNvbHVtbnMvUHJpbWl0aXZlRGF0YUZyYW1lQ29sdW1ucy9Eb3VibGVEYXRhRnJhbWVDb2x1bW4uY3M=) | `100.00% <ø> (ø)` | | | [.../PrimitiveDataFrameColumns/Int16DataFrameColumn.cs](https://app.codecov.io/gh/dotnet/machinelearning/pull/6872?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dotnet#diff-c3JjL01pY3Jvc29mdC5EYXRhLkFuYWx5c2lzL0RhdGFGcmFtZUNvbHVtbnMvUHJpbWl0aXZlRGF0YUZyYW1lQ29sdW1ucy9JbnQxNkRhdGFGcmFtZUNvbHVtbi5jcw==) | `100.00% <ø> (ø)` | | | [.../PrimitiveDataFrameColumns/Int32DataFrameColumn.cs](https://app.codecov.io/gh/dotnet/machinelearning/pull/6872?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dotnet#diff-c3JjL01pY3Jvc29mdC5EYXRhLkFuYWx5c2lzL0RhdGFGcmFtZUNvbHVtbnMvUHJpbWl0aXZlRGF0YUZyYW1lQ29sdW1ucy9JbnQzMkRhdGFGcmFtZUNvbHVtbi5jcw==) | `100.00% <ø> (ø)` | | | [.../PrimitiveDataFrameColumns/Int64DataFrameColumn.cs](https://app.codecov.io/gh/dotnet/machinelearning/pull/6872?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dotnet#diff-c3JjL01pY3Jvc29mdC5EYXRhLkFuYWx5c2lzL0RhdGFGcmFtZUNvbHVtbnMvUHJpbWl0aXZlRGF0YUZyYW1lQ29sdW1ucy9JbnQ2NERhdGFGcmFtZUNvbHVtbi5jcw==) | `100.00% <ø> (ø)` | | | ... and [20 more](https://app.codecov.io/gh/dotnet/machinelearning/pull/6872?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dotnet) | | ... and [22 files with indirect coverage changes](https://app.codecov.io/gh/dotnet/machinelearning/pull/6872/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dotnet)

[michaelgsharp]

/azp run

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