Migration script for master terraform state (count -> for_each)

[robinAwallace]

In the next release of kubespray there is a possibility to manage master nodes in a map instead of count number.

Create a migration script which moves to the new for_each approach.

1. Create a cluster using number_...
2. Run migration script
3. Show that terraform plan does not change anything.

For more information: https://github.com/kubernetes-sigs/kubespray/pull/8709