Remove null_count from ArrayData::try_new()

[HaoYang670]

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

Which issue does this PR close?

Closes #911.

Rationale for this change

Avoid the inconsistency of between ArrayData::null_count and ArrayData::null_nit_buffer.

(Sadly, we could not do any simplification in ArrayData::validate.)

Are there any user-facing changes?

The API of ArrayData::try_new()

[codecov-commenter]

Codecov Report

Merging #1721 (c2b5431) into master (7b164a0) will decrease coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #1721      +/-   ##
==========================================
- Coverage   83.32%   83.30%   -0.02%     
==========================================
  Files         195      195              
  Lines       56044    55978      -66     
==========================================
- Hits        46698    46635      -63     
+ Misses       9346     9343       -3     

Impacted Files	Coverage Δ
arrow/src/array/transform/mod.rs	86.85% <ø> (+0.05%)	⬆️
arrow/src/compute/util.rs	98.90% <ø> (-0.01%)	⬇️
arrow/src/array/data.rs	83.65% <100.00%> (-0.80%)	⬇️
parquet/src/encodings/encoding.rs	93.65% <0.00%> (+0.19%)	⬆️
arrow/src/datatypes/datatype.rs	65.79% <0.00%> (+0.37%)	⬆️

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[tustvold]

Looks good to me, thank you 👍

[viirya]

Looks good. Thanks @HaoYang670