ARROW-6269: [C++] check decimal precision in IPC code

[crepererum]

No description provided.

[pitrou]

Rebased and improved.

[pitrou]

+1, will wait for CI.

[codecov-io]

Codecov Report

Merging #5104 into master will increase coverage by 1.85%.
The diff coverage is 88.88%.

@@            Coverage Diff             @@
##           master    #5104      +/-   ##
==========================================
+ Coverage   87.35%    89.2%   +1.85%     
==========================================
  Files         920      750     -170     
  Lines      124475   107890   -16585     
  Branches     1437        0    -1437     
==========================================
- Hits       108730    96244   -12486     
+ Misses      15383    11646    -3737     
+ Partials      362        0     -362

Impacted Files	Coverage Δ
cpp/src/arrow/type.h	92.52% <ø> (ø)	⬆️
cpp/src/arrow/ipc/metadata_internal.cc	87.97% <100%> (+4.59%)	⬆️
cpp/src/arrow/type.cc	93.91% <87.5%> (+0.04%)	⬆️
go/arrow/math/uint64_amd64.go
go/arrow/memory/memory_avx2_amd64.go
rust/datafusion/src/execution/filter.rs
rust/arrow/src/csv/writer.rs
rust/datafusion/src/bin/main.rs
go/arrow/ipc/file_reader.go
js/src/builder/index.ts
... and 464 more

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[crepererum]

Sorry, I was busy since submitting this PR. Thanks @pitrou, looks really good now :)