[Java] Include compiled Flatbuffers sources in release artifacts

I'm seeing the flatc that's available in Maven foul up users because it depends on a version of glibc (2.14) which is too new for many enterprise Linux users. It would be better for the Arrow Java artifacts to not depend on flatc at all, if possible.

We could check the compiled sources into source control, but that seems less than ideal. Is there a clean way bundle them at packaging time?

**Reporter**: [Wes McKinney](https://issues.apache.org/jira/browse/ARROW-397) / @wesm

_{**Note**: *This issue was originally created as [ARROW-397](https://issues.apache.org/jira/browse/ARROW-397). Please see the [migration documentation](https://github.com/apache/arrow/issues/14542) for further details.*}

先檢視 issue 中連結的 migration 文件，以及 Arrow Java artifacts 的 Maven packaging 設定。確認目前 flatc 的使用方式，並定義一條在 packaging 時納入已編譯 FlatBuffers sources 的路徑，而不需要在使用時具備 flatc；完成的標準是，release artifacts 不再針對這些 sources 依賴該 binary。

由索引模型根據 Issue 內容生成。