Support for recursive globs

[torhovland]

When I have a nested tree of manifest files, this alone doesn't work:

data "kubectl_path_documents" "docs" {
  pattern = "${path.module}/manifests/**/*.yaml"
}

I need to do this as well in order to get the second level of directories:

data "kubectl_path_documents" "nested" {
  pattern = "${path.module}/manifests/**/**/*.yaml"
}