Better display of DataFrame in IEnumerable Visualizer

[TheJanzap]

Is your feature request related to a problem? Please describe. Currently, it is quite inconvenient to look at data inside of a DataFrame during debugging. It is possible to view the data via the "Results View" of the "Rows"/"Columns" properties, but with a lot of data, this gets inconvenient

Visual Studio added the IEnumerable Visualizer a while ago and I think it could significantly increase the debug experience, since it also allows to export data to CSV.

Currently, it is possible to have a view like this of the data:

This is not ideal, as in every row the whole DataFrame is inserted in the ._dataFrame column.

Describe the solution you'd like I'd like to see better support for the IEnumerable Visualizer, so when viewing rows in it, every column has its own field.

Describe alternatives you've considered If this is impractical, it would also help to just remove the _dataFrame column from the IEnumerable view to make CSV exports a lot more digestable.

[michaelgsharp]

@JakeRadMSFT @luisquintanilla