Added io_csv_read and io_csv_write feature

[ritchie46]

This feature gates io_csv into io_csv_read and io_csv_write in a backwards compatible manner.

io_csv = ["io_csv_read", "io_csv_write"]

closes #407

[codecov]

Codecov Report

Merging #408 (90fb423) into main (ee23796) will increase coverage by 0.00%.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #408   +/-   ##
=======================================
  Coverage   80.96%   80.96%           
=======================================
  Files         347      347           
  Lines       22141    22201   +60     
=======================================
+ Hits        17927    17976   +49     
- Misses       4214     4225   +11     

Impacted Files	Coverage Δ
src/io/csv/mod.rs	0.00% <ø> (ø)
src/compute/temporal.rs	83.78% <0.00%> (-10.07%)	⬇️
src/array/ord.rs	64.21% <0.00%> (-2.13%)	⬇️
tests/it/compute/temporal.rs	100.00% <0.00%> (ø)
src/compute/comparison/mod.rs	92.16% <0.00%> (ø)
src/compute/comparison/utf8.rs	67.41% <0.00%> (ø)
src/compute/comparison/binary.rs	67.41% <0.00%> (ø)
src/compute/comparison/boolean.rs	70.10% <0.00%> (ø)
src/compute/comparison/primitive.rs	91.01% <0.00%> (ø)
src/temporal_conversions.rs	84.15% <0.00%> (+1.98%)	⬆️
... and 1 more

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[jorgecarleitao]

Would you like to review this one @VasanthakumarV ?

[VasanthakumarV]

Changes look good @jorgecarleitao

Only minutiae is whether, if we will need individual #[cfg_attr(docsrs, doc(cfg(feature = "io_csv")))] like attributes on the read and write module inside csv

[jorgecarleitao]

Thanks a lot, @ritchie46 !

As @VasanthakumarV mentioned, we need the doc(cfg(feature = so that the API docs show the module with "This is supported on crate feature X only." (see https://docs.rs/arrow2/0.5.2/arrow2/compute/index.html).