Depend on lintrunner-adapters pypi instead (#251)

Summary:
Pull Request resolved: https://github.com/pytorch/executorch/pull/251

Currently we are calling third-party/pytorch/tools/

But the adapters are already in pypi. Let's just depend on that.

That way, we don't have to do sketchy things like download arbitrary binary from s3 for clang formatter.

Reviewed By: digantdesai

Differential Revision: D49098183

fbshipit-source-id: 85bb829adbcbd031b888762e94e08415a99e626e