feat: add chapter_binary_search by dart

[JeffersonHuang]

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目标元素 6 的索引 = 2
目标元素 6 的索引 = 2

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1 Ignored Deployment

Name	Status	Preview	Comments	Updated (UTC)
hello-algo	⬜️ Ignored (Inspect)			May 19, 2023 2:21am