Fix reading dictionaries from nested structs in ipc StreamReader

[dispanser]

Which issue does this PR close?

Closes #1549.

Rationale for this change

Fixing a bug in the ipc stream reader, aligning with the FileReader implementation.

What changes are included in this PR?

The actual bugfix is 4 characters, but this PR also includes a test to reproduce the bug.

Are there any user-facing changes?

No documetation changes needed.

[alamb]

Thank you @dispanser ! @viirya I wonder if you might have a chance to review this PR?

[viirya]

Thanks @dispanser @alamb. Yeah, I will review this today.

[viirya]

I think the fix is correct as we do this to fill dictionaries_by_field.

for (i, field) in schema.all_fields().iter().enumerate() {
   dictionaries_by_field[i] = ...
}

Actually, in FileReader, it does the same:

let mut dictionaries_by_field = vec![None; schema.all_fields().len()];

[viirya]

lgtm, only one minor comment.

[codecov-commenter]

Codecov Report

Merging #1550 (cd838e5) into master (68038f5) will increase coverage by 0.01%.
The diff coverage is 100.00%.

❗ Current head cd838e5 differs from pull request most recent head 30f7b30. Consider uploading reports for the commit 30f7b30 to get more accurate results

@@            Coverage Diff             @@
##           master    #1550      +/-   ##
==========================================
+ Coverage   82.82%   82.84%   +0.01%     
==========================================
  Files         190      190              
  Lines       54941    54966      +25     
==========================================
+ Hits        45507    45535      +28     
+ Misses       9434     9431       -3     

Impacted Files	Coverage Δ
arrow/src/ipc/reader.rs	88.28% <100.00%> (+0.48%)	⬆️
arrow/src/array/transform/mod.rs	86.46% <0.00%> (+0.11%)	⬆️
parquet/src/encodings/encoding.rs	93.56% <0.00%> (+0.18%)	⬆️
parquet_derive/src/parquet_field.rs	66.43% <0.00%> (+0.22%)	⬆️

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[viirya]

lgtm

[tustvold]

Looks good to me, thank you @dispanser