[C++] Improve Build Time Through ArrayData forward Declarations

[WillAyd]

Describe the enhancement requested

When reviewing the output of ClangBuildAnalyzer, it appears that the arrow/array/data.h header is considered to be the most expensive include:

**** Expensive headers:
205021 ms: /home/willayd/clones/arrow/cpp/src/arrow/array/data.h (included 168 times, avg 1220 ms), included via:
  27x: array.h array_base.h 
  11x: array_base.h 
  6x: api_scalar.h datum.h 
  6x: function.h kernel.h exec.h 
  5x: <direct include>
  5x: builder_primitive.h builder_base.h array_base.h 
  ...

158726 ms: /home/willayd/clones/arrow/cpp/src/arrow/array/array_base.h (included 168 times, avg 944 ms), included via:
  28x: array.h 
  11x: <direct include>
  6x: api_scalar.h datum.h scalar.h extension_type.h 
  6x: function.h kernel.h exec.h expression.h datum.h scalar.h extension_type.h 
  5x: builder_primitive.h builder_base.h 
  5x: gtest.h array.h 
  ...

121366 ms: /home/willayd/clones/arrow/cpp/src/arrow/type.h (included 202 times, avg 600 ms), included via:
  13x: array.h array_base.h data.h statistics.h 
  12x: array.h array_base.h data.h cassert 
  9x: array_base.h data.h statistics.h 
  6x: api_scalar.h datum.h data.h cassert statistics.h 
  5x: data.h statistics.h 
  5x: builder_primitive.h builder_base.h array_base.h data.h cassert 
  ...

According to iwyu, there are a dozen or so instances where inclusion of that header can be replaced with a forward declaration of ArrayData, which should help reduce build time

Component(s)

C++