[FEA] Port cuIO JSON reader to cudf::column types

[mjsamoht]

Is your feature request related to a problem? Please describe.
This issue tracks the effort for moving the cuIO JSON reader to using the new column design and associated infrastructure. It is a continuation of #2954 where all other cuIO readers and writers were moved in release 0.11.

Describe the solution you'd like
Currently, cuIO JSON reader uses wrappers around the C-style gdf_column to aid in storing/accessing column metadata and allocating/deallocating memory. We should be able to get rid of the custom C++ wrappers and directly use the cudf::column and cudf::table.

Describe alternatives you've considered
We may or may not need some sort of temporary wrapper or custom column class still within cuIO to temporary hold column metadata that's format-specific, for delayed column creation to save memory or other usage. The returned columns will be cudf::column and cudf::table though.

Additional context
See other porting efforts for libcudf.

[mjsamoht]

@nvdbaranec are you still working on this?

[nvdbaranec]

Yes. Hoping to put up a PR today.