ARROW-5551: [Go] implement FixedSizeArrays with 2-buffers layout

[sbinet]

No description provided.

[codecov-io]

Codecov Report

Merging #4517 into master will decrease coverage by 7.18%.
The diff coverage is 69.44%.

@@            Coverage Diff             @@
##           master    #4517      +/-   ##
==========================================
- Coverage   80.32%   73.13%   -7.19%     
==========================================
  Files         201       76     -125     
  Lines       13828     6370    -7458     
  Branches     1253        0    -1253     
==========================================
- Hits        11107     4659    -6448     
+ Misses       2475     1474    -1001     
+ Partials      246      237       -9

Impacted Files	Coverage Δ
go/arrow/ipc/file_reader.go	63.57% <100%> (+2.85%)	⬆️
go/arrow/array/fixedsize_binary.go	100% <100%> (+25.58%)	⬆️
go/arrow/ipc/writer.go	75.78% <43.75%> (-2.18%)	⬇️
go/arrow/array/fixedsize_binarybuilder.go	85.24% <77.77%> (-5.78%)	⬇️
r/src/recordbatch.cpp
r/R/Table.R
r/src/symbols.cpp
r/R/Column.R
r/src/arrow_types.h
js/src/enum.ts
... and 123 more

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