*: introduce contrib for runkperf

[fuweid]

The contrib is to hold extra commands, for example, ekswarmup is used to trigger EKS apiserver's cores.
It will hold benchmark test suites in the following-up.

The runkperf is entrypoint for all the extra commands. It's also installed into kperf image.

Currently, the runkperf ekswarmup is used to trigger EKS to bump apiserver's cores into 8 at least.
Most of settings are fixed. We should make it configurable in the future. This command requires three nodepools, like

apiVersion: eksctl.io/v1alpha5
kind: ClusterConfig

metadata:
  name: XYZ
  region: us-east-2
  version: "1.27"

nodeGroups:
  - name: virtualnode
    instanceType: m4.2xlarge // used to hold 100 virtual nodes
    desiredCapacity: 5
  - name: runner
    instanceType: m4.4xlarge // used to hold kperf runner
    desiredCapacity: 3
  - name: placeholder 
    instanceType: m4.large // used to share providerID to virtual nodes, just in case that virtual nodes are deleted by EKS cloud provider
    desiredCapacity: 1

Ideally, it will take 17 minutes for warmup.