Moved is_ordered from Field to DataType::Dictionary

[jorgecarleitao]

This allows users of DictionaryArray to check the boolean in its data_type, to specialize sorting of the values by taking the boolean into account.

[codecov]

Codecov Report

Merging #711 (8d4f9b8) into main (87a08f4) will increase coverage by 0.06%.
The diff coverage is 70.14%.

@@            Coverage Diff             @@
##             main     #711      +/-   ##
==========================================
+ Coverage   70.17%   70.23%   +0.06%     
==========================================
  Files         309      309              
  Lines       16802    16820      +18     
==========================================
+ Hits        11790    11814      +24     
+ Misses       5012     5006       -6     

Impacted Files	Coverage Δ
src/compute/arithmetics/mod.rs	69.81% <0.00%> (ø)
src/compute/cast/dictionary_to.rs	24.39% <0.00%> (ø)
src/compute/take/mod.rs	65.85% <ø> (ø)
src/io/avro/read/nested.rs	44.44% <ø> (ø)
src/io/json_integration/mod.rs	0.00% <0.00%> (ø)
src/io/parquet/read/primitive/mod.rs	41.02% <0.00%> (ø)
src/compute/cast/mod.rs	93.91% <40.00%> (ø)
src/compute/sort/mod.rs	26.66% <50.00%> (ø)
src/io/json_integration/schema.rs	45.79% <63.63%> (-0.03%)	⬇️
src/array/dictionary/mod.rs	63.07% <66.66%> (-0.99%)	⬇️
... and 21 more

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