Added terraform support for Exoscale (#7141)

contrib/terraform/exoscale/README.md

contrib/terraform/exoscale/default.tfvars

contrib/terraform/exoscale/main.tf

...rib/terraform/exoscale/modules/kubernetes-cluster/main.tf

...b/terraform/exoscale/modules/kubernetes-cluster/output.tf

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

...erraform/exoscale/modules/kubernetes-cluster/variables.tf

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

contrib/terraform/exoscale/output.tf

contrib/terraform/exoscale/templates/inventory.tpl

contrib/terraform/exoscale/variables.tf

contrib/terraform/exoscale/versions.tf