Adding scripts to make it easy to run junit test. These are named
out/bin/run_<junit_suite_name>.

Moving the helper scripts that our test runner uses to run the
junit test suites. These scripts are not meant to be run except
by the test runner. Moving them into out/bin/helper/<script_names>
so people don't accidently try to run them.

BUG=511999

Review URL: https://codereview.chromium.org/1674353004

Cr-Commit-Position: refs/heads/master@{#375603}