Add Infrastructure testing and Pipeline

[TsuyoshiUshio]

As a developer, I'd like to have an infrastructure integration testing, so that we can validate pull request.
I'm planning to implement it as terratest. The scenario will be:

• Create an AKS cluster with RBAC enabled
• Push new image to private ACR
• deploy kedacore
• deploy keda-scaler-durable-functions with helm. It uses new images.
• deploy sample durable functions
• Start durable functions several times from example directory
• Check if it scare more than two
• Clean up the resources

Success Criteria

• Integration testing is implemented
• PR validation works with GitHub Action when we add full-ci label on the target PR.

[tomkerkhove]

With Helm 3 you don't need Tiller anymore! 🎉

[TsuyoshiUshio]

You right. :) I remove it.