add dictionary serialization for csv-writer

[ritchie46]

This PR adds csv serializations for dictionary encoded arrays. I've only implemented them for typically rust indexes usize atm. It would be trivial to add other indexes, but if no-one (don't know how they are used in the wild) uses them it might not be worth the compilation.

closes #508

[codecov]

Codecov Report

Merging #515 (a63fbe4) into main (e77d4e1) will decrease coverage by 0.00%.
The diff coverage is 75.86%.

@@            Coverage Diff             @@
##             main     #515      +/-   ##
==========================================
- Coverage   80.18%   80.17%   -0.01%     
==========================================
  Files         381      381              
  Lines       23665    23693      +28     
==========================================
+ Hits        18975    18997      +22     
- Misses       4690     4696       +6     

Impacted Files	Coverage Δ
src/io/csv/write/serialize.rs	52.58% <70.83%> (+5.27%)	⬆️
tests/it/io/csv/write.rs	96.22% <100.00%> (+0.39%)	⬆️
src/compute/arithmetics/time.rs	44.89% <0.00%> (-2.05%)	⬇️
src/bitmap/utils/slice_iterator.rs	92.53% <0.00%> (-1.50%)	⬇️
src/io/ipc/write/common.rs	75.64% <0.00%> (-0.65%)	⬇️
src/io/avro/read/schema.rs	55.95% <0.00%> (+1.19%)	⬆️
src/types/index.rs	78.78% <0.00%> (+6.06%)	⬆️

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[jorgecarleitao]

Thanks a lot, Ritchie!

Almost there imo:

1. need to add the bound checks
2. some tests :P