`dt` command for bisecting a Flutter regression

[elliette]

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 #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.