Add status method to Sandbox Client and also add unit tests associated with it.#280

SHRUTI6991 wants to merge 2 commits intokubernetes-sigs:mainkubernetes-sigs/agent-sandbox:mainfrom

SHRUTI6991:core_execution_pod_statusSHRUTI6991/agent-sandbox-initial-playing:core_execution_pod_statusCopy head branch name to clipboard