Rename container-linux modules to flatcar-linux

* CoreOS Container Linux was deprecated in v1.18.3
* Continue transitioning docs and modules from supporting
both CoreOS and Flatcar "variants" of Container Linux to
now supporting Flatcar Linux and equivalents

Action Required: Update the Flatcar Linux modules `source`
to replace `s/container-linux/flatcar-linux`. See docs for
examples

aws/flatcar-linux/kubernetes/workers/workers.tf

@@ -0,0 +1,92 @@
+# Workers AutoScaling Group
+resource "aws_autoscaling_group" "workers" {
+  name = "${var.name}-worker ${aws_launch_configuration.worker.name}"
+
+  # count
+  desired_capacity          = var.worker_count
+  min_size                  = var.worker_count
+  max_size                  = var.worker_count + 2
+  default_cooldown          = 30
+  health_check_grace_period = 30
+
+  # network
+  vpc_zone_identifier = var.subnet_ids
+
+  # template
+  launch_configuration = aws_launch_configuration.worker.name
+
+  # target groups to which instances should be added
+  target_group_arns = flatten([
+    aws_lb_target_group.workers-http.id,
+    aws_lb_target_group.workers-https.id,
+    var.target_groups,
+  ])
+
+  lifecycle {
+    # override the default destroy and replace update behavior
+    create_before_destroy = true
+  }
+
+  # Waiting for instance creation delays adding the ASG to state. If instances
+  # can't be created (e.g. spot price too low), the ASG will be orphaned.
+  # Orphaned ASGs escape cleanup, can't be updated, and keep bidding if spot is
+  # used. Disable wait to avoid issues and align with other clouds.
+  wait_for_capacity_timeout = "0"
+
+  tags = [
+    {
+      key                 = "Name"
+      value               = "${var.name}-worker"
+      propagate_at_launch = true
+    },
+  ]
+}
+
+# Worker template
+resource "aws_launch_configuration" "worker" {
+  image_id          = local.ami_id
+  instance_type     = var.instance_type
+  spot_price        = var.spot_price > 0 ? var.spot_price : null
+  enable_monitoring = false
+
+  user_data = data.ct_config.worker-ignition.rendered
+
+  # storage
+  root_block_device {
+    volume_type = var.disk_type
+    volume_size = var.disk_size
+    iops        = var.disk_iops
+    encrypted   = true
+  }
+
+  # network
+  security_groups = var.security_groups
+
+  lifecycle {
+    // Override the default destroy and replace update behavior
+    create_before_destroy = true
+    ignore_changes        = [image_id]
+  }
+}
+
+# Worker Ignition config
+data "ct_config" "worker-ignition" {
+  content  = data.template_file.worker-config.rendered
+  strict   = true
+  snippets = var.snippets
+}
+
+# Worker Container Linux config
+data "template_file" "worker-config" {
+  template = file("${path.module}/cl/worker.yaml")
+
+  vars = {
+    kubeconfig             = indent(10, var.kubeconfig)
+    ssh_authorized_key     = var.ssh_authorized_key
+    cluster_dns_service_ip = cidrhost(var.service_cidr, 10)
+    cluster_domain_suffix  = var.cluster_domain_suffix
+    cgroup_driver          = local.channel == "edge" ? "systemd" : "cgroupfs"
+    node_labels            = join(",", var.node_labels)
+  }
+}
+