[Java] Optimize bit operations performance

From @animeshtrivedi's benchmark finding:

2) Materialize values from Validity and Value direct buffers instead of
calling getInt() function on the IntVector. This is implemented as a new
Unsafe reader type (

)

3) Optimize bitmap operation to check if a bit is set or not (

)

**Reporter**: [Li Jin](https://issues.apache.org/jira/browse/ARROW-3495) / @icexelloss
#### Subtasks:
- [X] [[Java] Remove Long.bitCount with simple bitmap operations](https://github.com/apache/arrow/issues/20485)
#### PRs and other links:
- [GitHub Pull Request apache/arrow#5930](https://github.com/apache/arrow/pull/5930)

_{**Note**: *This issue was originally created as [ARROW-3495](https://issues.apache.org/jira/browse/ARROW-3495). Please see the [migration documentation](https://github.com/apache/arrow/issues/14542) for further details.*}

從 benchmark 中對 ArrowReaderUnsafe.java 的參照開始，檢查 Apache Arrow PR #5930，然後檢視已完成的點陣圖操作子任務，以確定還剩下什麼。將要求的直接緩衝區具現化和點陣圖檢查與現有的 Java 實作進行比較；完成的標準是實作剩餘的最佳化，並驗證其效能影響。

由索引模型根據 Issue 內容生成。