Remove redundant has_ methods in ColumnChunkMetaData

[shanisolomon]

Which issue does this PR close?

Closes #1344.

Rationale for this change

Remove redundant has_ methods for optional column metadata members as they could be access by if let(Some) = field.

[codecov-commenter]

Codecov Report

Merging #1345 (6270107) into master (ecba7dc) will decrease coverage by 0.00%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1345      +/-   ##
==========================================
- Coverage   83.04%   83.04%   -0.01%     
==========================================
  Files         181      181              
  Lines       52937    52926      -11     
==========================================
- Hits        43960    43950      -10     
+ Misses       8977     8976       -1     

Impacted Files	Coverage Δ
parquet/src/file/metadata.rs	93.88% <ø> (+0.43%)	⬆️
parquet/src/file/serialized_reader.rs	94.60% <ø> (-0.04%)	⬇️
arrow/src/datatypes/datatype.rs	66.40% <0.00%> (-0.40%)	⬇️
arrow/src/array/transform/mod.rs	84.39% <0.00%> (-0.14%)	⬇️
arrow/src/datatypes/field.rs	54.10% <0.00%> (+0.30%)	⬆️

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[sunchao]

This looks fine. I'm just not sure if it'll break some existing code depending on the crate though since they are public.

[shanisolomon]

@sunchao IIUC the methods were exposed part of v9.1 which hasn't been published yet?

[sunchao]

Oh I see. Then LGTM.

[shanisolomon]

@alamb Do you mind please assisting with merging? :)

[sunchao]

Merged, thanks @shanisolomon !

[alamb]

Sorry for the delay @shanisolomon -- I was out last week

[alamb]

Since these functions were released in 9.1.0 removing them is technically a breaking change, so marking them as such