Stress and Load test helm chart to validate loads

[Abhi94N]

1. Create a script to launch multiple single-user notebooks at once from the hub.
2. Collect data for stress testing
3. Repeat steps 1 and 2 for graders by launching multiple graders from the grader-setup-service
4. Take a look into kboom for load testing

[jgwerner]

@Abhi94N closing and moving to the illumidesk/infra repo.