[code-reflection] RFR: OnnxRuntime and OnnxProtoBuilder continuation

[Adam Sotona]

OnnxRuntime and OnnxProtoBuilder continuation

-------------

Commit messages:
 - CNNTest cleanup + weight tensors stored in little-endian for direct mapping
 - OnnxProtoPrinter implemenation
 - OnnxProtoBuilder support for tuple results + test

Changes: https://git.openjdk.org/babylon/pull/320/files
  Webrev: https://webrevs.openjdk.org/?repo=babylon&pr=320&range=00
  Stats: 469 lines in 26 files changed: 330 ins; 63 del; 76 mod
  Patch: https://git.openjdk.org/babylon/pull/320.diff
  Fetch: git fetch https://git.openjdk.org/babylon.git pull/320/head:pull/320

PR: https://git.openjdk.org/babylon/pull/320