Move the Core Benchmarks Runner to its own repo

Move the Qt Core Benchmarks Runner to the newly created repo: qtbots/qtcorebenchmarkrunner

You should move the files to a fresh repo, create an initial commit, and then push to refs/heads/dev in the new qtcorebenchmarksrunner repo. Contact daniel.smith for temporary push rights so you can push directly to a branch.

Once the new repo is populated, submit a change to qtqa to remove the old code, referencing this ticket with a Task-number footer.