Remove arrow array reader (#1197)

[tustvold]

Which issue does this PR close?

This is preventing fixing #1230 and interfering with progress on #1154 and #1225 and so I think the time has come to remove this.

Closes #1197.

Rationale for this change

See ticket

What changes are included in this PR?

Removes ArrowArrayReader

Are there any user-facing changes?

No, this was made an experimental API in #1134

FYI @yordan-pavlov

[codecov-commenter]

Codecov Report

Merging #1234 (b8e1c84) into master (d801ac2) will increase coverage by 0.11%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1234      +/-   ##
==========================================
+ Coverage   82.82%   82.94%   +0.11%     
==========================================
  Files         179      178       -1     
  Lines       52170    51346     -824     
==========================================
- Hits        43210    42589     -621     
+ Misses       8960     8757     -203     

Impacted Files	Coverage Δ
parquet/src/util/test_common/page_util.rs	88.88% <0.00%> (-2.03%)	⬇️
parquet/src/util/memory.rs	89.25% <0.00%> (-1.87%)	⬇️
arrow/src/array/transform/mod.rs	84.78% <0.00%> (-0.79%)	⬇️
arrow/src/datatypes/field.rs	53.79% <0.00%> (-0.31%)	⬇️
parquet/src/encodings/encoding.rs	93.52% <0.00%> (-0.20%)	⬇️

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[yordan-pavlov]

ArrowArrayReader was quite self-contained so, as expected, easy to remove - thanks @tustvold;

[alamb]

Thanks @yordan-pavlov and @tustvold