Column to JCUDF row for tables with strings (NVIDIA#10235)

This is the code for the column to row portion of the string work. This code will convert a table that includes strings into the JCUDF row format. This depends on NVIDIA#10157 and as such, is a draft PR until that is merged. I am putting this up now so people working on reviewing that PR can see where it is headed.

closes NVIDIA#10234

Authors:
  - Mike Wilson (https://github.com/hyperbolic2346)

Approvers:
  - Nghia Truong (https://github.com/ttnghia)
  - MithunR (https://github.com/mythrocks)
  - https://github.com/nvdbaranec

URL: rapidsai/cudf#10235