`dt` command for bisecting a Flutter regression

There has been a few times I've had to manually perform a binary search across Flutter commits to determine which commit caused a regression. Most recently with https://github.com/flutter/devtools/issues/9456

And each time I think, there really should be a `dt` command (e.g `dt flutter-bisect --from commitA --to commitB --test=path/to/test`) that performs the binary search and runs the regressed test for me to determine the commit that introduced the regression.

首先定位现有的 `dt` 命令入口点，并检查如何处理 Flutter 提交以及 `--test=path/to/test` 目标。定义 bisect 范围、提交 checkout 和测试执行流程，然后确认该命令能够识别引入回归的第一个提交，并处理失败或无效范围。

由索引模型根据 Issue 内容生成。