ARROW-11246: [Rust] Add type to Unexpected accumulator state error

[ovr]

I am getting a bug with an error: Unexpected accumulator state, but It's not possible to understand what value was passed when the exception is done on the user's side. I add type to the error message to make investigation of the bug more easy.

[github-actions]

https://issues.apache.org/jira/browse/ARROW-11246

[codecov-io]

Codecov Report

Merging #9201 (e2179b9) into master (6da7718) will increase coverage by 0.00%.
The diff coverage is 62.90%.

@@ Coverage Diff @@## master #9201 +/- ##
=======================================
Coverage 81.55% 81.56% =======================================
Files 215 215 Lines 51600 51656 +56 =======================================
+ Hits 42084 42133 +49 - Misses 9516 9523 +7 

Impacted Files	Coverage Δ
rust/arrow/src/datatypes.rs	78.59% <0.00%> (-0.16%)	⬇️
...tafusion/src/physical_plan/distinct_expressions.rs	91.26% <0.00%> (-0.45%)	⬇️
...ust/datafusion/src/physical_plan/hash_aggregate.rs	84.65% <0.00%> (ø)
rust/datafusion/src/physical_plan/hash_join.rs	84.27% <0.00%> (ø)
rust/datafusion/src/physical_plan/common.rs	78.78% <73.58%> (+13.57%)	⬆️
rust/parquet/src/encodings/encoding.rs	95.43% <0.00%> (+0.19%)	⬆️

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[alamb]

I apologize for the delay in merging Rust PRs -- the 3.0 release is being finalized now and are planning to minimize entropy by postponing merging changes not critical for the release until the process was complete. I hope the process is complete in the next few days. There is more discussion in the mailing list

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 3 lines in your changes missing coverage. Please review.

Project coverage is 81.56%. Comparing base (6da7718) to head (e2179b9).

Files with missing lines	Patch %	Lines
...tafusion/src/physical_plan/distinct_expressions.rs	0.00%	3 Missing ⚠️

Additional details and impacted files

@@ Coverage Diff @@## master #9201 +/- ##
=======================================
Coverage 81.55% 81.56% =======================================
Files 215 215 Lines 51600 51656 +56 =======================================
+ Hits 42084 42133 +49 - Misses 9516 9523 +7 

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