[code-reflection] RFR: OnnxProtoModel implementation [v3]

[Adam Sotona]

> Changes in this PR:
> - `OnnxProtoModel` implementation replacing and enhancing basic `OnnxProtoPrinter` functionality
> - added missing copyright headers

Adam Sotona has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 12 commits:

 - OnnxPartialEvaluator sync with the latest changes
   
 - Merge remote-tracking branch 'babylon/code-reflection' into onnx-parser
 - OnnxProtoModel::toText improved to allow dump all data
   
 - copyright headers
   
 - fixed OnnxProtoModel
   
 - Merge remote-tracking branch 'babylon/code-reflection' into onnx-parser
   
 - OnnxProtoModel implementation replaces OnnxProtoPrinter
   
 - draft of ModelProto
   
 - draft of OnnxProtoParser
   
 - draft of OnnxProtoParser
   
 - ... and 2 more: https://git.openjdk.org/babylon/compare/d41b2ba4...c93d78ef

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Changes: https://git.openjdk.org/babylon/pull/399/files
  Webrev: https://webrevs.openjdk.org/?repo=babylon&pr=399&range=02
  Stats: 795 lines in 8 files changed: 537 ins; 256 del; 2 mod
  Patch: https://git.openjdk.org/babylon/pull/399.diff
  Fetch: git fetch https://git.openjdk.org/babylon.git pull/399/head:pull/399

PR: https://git.openjdk.org/babylon/pull/399