Create container to run terraform quickstarts

[nikkelma]

Terraform-based quickstarts require the terraform binary and terraform-provider-rke to be installed where the quickstart will run.

As an alternative, create a container that contains all required tools for running the quickstart, only requiring configuration to be passed in via volumes or arguments. This container should include the terraform binary, provider binaries (official and community) and should require an argument to choose which infrastructure provider folder to deploy.

[nikkelma]

The move to Terraform 0.13 alone removes much of this need, as no provider installation is required. However, once #81 is implemented, multiple terraform apply calls will be required, meaning the quickstart could move to a multi-step process. To remain a single-step process, a few different solutions could be used:

• docker container with shell scripts to coordinate all apply operations
• Go CLI for cross-platform coordination of apply operations
• Terragrunt with post-apply hooks calling the next apply operation