Core: Add e2e test run against k8shim master branch

When code is pushed in yunikorn-core to github, we run unit tests, but there are no tests run on the latest code from yunikorn-k8shim to verify that functionality has not broken. There have been several instances where this has resulted in broken code going a long time without being discovered. We should add a pre-commit hook to build yunikorn-core PRs against the latest yunikorn-k8shim master branch and execute at least one e2e test run to ensure that we don't introduce regressions.