Minor: Refine OffsetSizeTrait to extend num::Integer

[HaoYang670]

Signed-off-by: remzi 13716567376yh@gmail.com

Which issue does this PR close?

None.

Rationale for this change

Offsets are always integers, so OffsetSizeTrait should be a superset of Interger.

What changes are included in this PR?

Add Integer, remove Num and Ord.

Are there any user-facing changes?

No.

[codecov-commenter]

Codecov Report

Merging #1702 (9c96cdc) into master (ff182f1) will increase coverage by 0.00%.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #1702   +/-   ##
=======================================
  Coverage   83.27%   83.28%           
=======================================
  Files         195      195           
  Lines       55937    55937           
=======================================
+ Hits        46584    46587    +3     
+ Misses       9353     9350    -3     

Impacted Files	Coverage Δ
arrow/src/array/array_list.rs	96.16% <ø> (ø)
arrow/src/array/transform/mod.rs	87.02% <0.00%> (+0.11%)	⬆️
parquet_derive/src/parquet_field.rs	66.21% <0.00%> (+0.22%)	⬆️
arrow/src/datatypes/datatype.rs	65.45% <0.00%> (+0.36%)	⬆️

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[alamb]

Makes sense to me

[alamb]

cc @tustvold