[Integration] Add endianness "gold" integration file for decimal256

[asfimport]

Decimal256 data is missing from the current little-/big-endian "gold" integration files in the arrow-testing repository:

https://github.com/apache/arrow-testing/tree/master/data/arrow-ipc-stream/integration/1.0.0-littleendian

 

Reporter: Antoine Pitrou / @pitrou
Assignee: Kazuaki Ishizaki / @kiszk

PRs and other links:

• GitHub Pull Request #58

_{Note: This issue was originally created as ARROW-11666. Please see the migration documentation for further details.}

[asfimport]

Antoine Pitrou / @pitrou:
cc @kiszk could you do this? It requires generating the files on both a little- and big-endian platform.

[asfimport]

Kazuaki Ishizaki / @kiszk:
Sure, I will do this.

[asfimport]

Kazuaki Ishizaki / @kiszk:
This was already merged at apache/arrow-testing#58