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ARROW-8301: [R] Handle ChunkedArray and Table in C data interface

In terms of number of lines of code, this wasn't bad, though I don't know how efficient these methods are. Maybe there's a better way

The one thing that would be lost is any metadata attached to the Table schema because the Table is reconstructed from its ChunkedArrays without schema. I wonder if we could export the Schema on its own--the existing `_export_to_c`/`_import_from_c` methods take both an array pointer and a schema pointer.

Closes #7648 from nealrichardson/r-py-tables

Authored-by: Neal Richardson <neal.p.richardson@gmail.com>
Signed-off-by: Neal Richardson <neal.p.richardson@gmail.com>