Turn ingress TestCheck into an E2e test

[mumoshu]

This modifies the ingress checker in several ways to make the ingress checker's TestCheck an E2E test:

• Added the checker an ability to send HTTP get request to the specified HTTP endpoint to verify the ingress controller and the ingress resource is working
• Adds NoHTTPCheck similar to the existing NoDnsCheck to opt-out of doing the HTTP check
• Fixed the test deployment's container port and service targetPort to use 80 instead of 8080, as the container seems to be listening on 80 instead of the previous value 8080
• Added ProcessHandle and StartProcess test helpers to automate running and stopping cluster-provider-kind. I'll try to move this to testkit later

[cw-sakamoto]

@mumoshu Thank you for your contribution!