Write FixedLenByteArray stats for FixedLenByteArray columns (not ByteArray stats)

[alamb]

Which issue does this PR close?

Resolves #660

Rationale for this change

FixedLenByteArray columns were writing the wrong type of statistics

What changes are included in this PR?

Write FixedLenByteArray stats for FixedLenByteArray columns (not ByteArray stats)

Are there any user-facing changes?

FixedLenByteArray statistics are written rather than ByteArray statistics. I am not sure if this is a user visible change however (see description on #661 (comment))

[codecov-commenter]

Codecov Report

Merging #662 (18349ac) into master (6bf1988) will decrease coverage by 0.06%.
The diff coverage is 85.39%.

❗ Current head 18349ac differs from pull request most recent head 67add39. Consider uploading reports for the commit 67add39 to get more accurate results

@@            Coverage Diff             @@
##           master     #662      +/-   ##
==========================================
- Coverage   82.50%   82.43%   -0.07%     
==========================================
  Files         168      168              
  Lines       47249    47325      +76     
==========================================
+ Hits        38984    39014      +30     
- Misses       8265     8311      +46     

Impacted Files	Coverage Δ
parquet/src/column/writer.rs	92.81% <85.36%> (-0.49%)	⬇️
parquet/src/data_type.rs	77.29% <85.71%> (+0.75%)	⬆️
arrow/src/array/transform/boolean.rs	76.92% <0.00%> (-7.70%)	⬇️
arrow/src/array/transform/utils.rs	95.00% <0.00%> (-5.00%)	⬇️
arrow/src/array/equal_json.rs	85.21% <0.00%> (-3.48%)	⬇️
arrow/src/tensor.rs	85.00% <0.00%> (-2.50%)	⬇️
parquet/src/column/page.rs	97.36% <0.00%> (-1.32%)	⬇️
arrow/src/array/equal/utils.rs	74.00% <0.00%> (-1.00%)	⬇️
parquet/src/record/api.rs	91.60% <0.00%> (-0.88%)	⬇️
parquet/src/file/statistics.rs	93.80% <0.00%> (-0.83%)	⬇️
... and 17 more

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[sunchao]

LGTM