improvement: Remove dependency on external template provider (#854)

* Remove template_file for generating kubeconfig

Push logic from terraform down to the template. Makes the formatting
slightly easier to follow

* Remove template_file for generating userdata

Updates to the eks_cluster now do not trigger recreation of launch
configurations

* Remove template_file for LT userdata

* Remove template dependency

versions.tf

@@ -5,7 +5,6 @@ terraform {
     aws        = ">= 2.52.0"
     local      = ">= 1.2"
     null       = ">= 2.1"
-    template   = ">= 2.1"
     random     = ">= 2.1"
     kubernetes = ">= 1.11.1"
   }