Added terraform script for Hetzner cloud (#8053)

contrib/terraform/hetzner/README.md

contrib/terraform/hetzner/default.tfvars

contrib/terraform/hetzner/main.tf

contrib/terraform/hetzner/modules/kubernetes-cluster/main.tf

...ib/terraform/hetzner/modules/kubernetes-cluster/output.tf

...zner/modules/kubernetes-cluster/templates/cloud-init.tmpl

...terraform/hetzner/modules/kubernetes-cluster/variables.tf

.../terraform/hetzner/modules/kubernetes-cluster/versions.tf

contrib/terraform/hetzner/output.tf

contrib/terraform/hetzner/templates/inventory.tpl

contrib/terraform/hetzner/variables.tf

contrib/terraform/hetzner/versions.tf