Isolate SDK and DNUP Pipelines and Checks

[nagilson]

📓 Summary

Try to isolate the pipelines for the uninstall tool and other sdk content from the bootstrapper. If we can make changes to isolated code in the bootstrapper folder, ideally we shouldn't need to run the CI for the uninstall tool which will make us progress and merge PRs much faster.

Additional Context

Not sure if this is configurable via the GH Repo which requires steps to be run for the entire repo...

Blocked Until These Issues Are Done:

dotnet/cli-lab#347