Add DateTime supports and tests to DataFrame

[eerhardt]

We currently don't have explicit tests for DateTime columns. We should add some tests and support in areas, ex. Arrow and IDataView integrations.

[pgovind]

Got to fix this ASAP. The Description method fails with a DateTime column because it tries to calculate DateTimeColumn.Max(). The easiest way to get full coverage for DateTime columns is to add it to the MakeDataFrameWithAllMutableColumnTypes method and fix the unit tests that fail

[rosebyte]

DataFrame now has first-class DateTimeDataFrameColumn support across CSV, Arrow and IDataView conversion, together with comparison and aggregation tests.