More dynamic local-storage-provisioner approach (#3472)

* Makes local volume provisioner more dynamic

* Correct variable name in local storage provisioner defaults

* Updates external-provisioner readme

* Updates variable naming to be more clear, more documentation, fixes sample inventory

* Variable refactor, untangled some jinja2 loops

* Corrects variable name

* No variable substitution in dict keys, replaced with anchor

* Fixes default storage_classes dict, inline docs

* Fixes spelling in inline docs

* Addresses comments in review

* Updates all the defaults

* Fix failing CI task

* Fixes external provisioner daemonset

roles/kubespray-defaults/defaults/main.yaml

@@ -314,10 +314,15 @@ kube_feature_gates: |-
   {%- endif %}
 
 # Local volume provisioner storage classes
-local_volume_provisioner_storage_classes:
-  - name: "{{ local_volume_provisioner_storage_class | default('local-storage') }}"
-    host_dir: "{{ local_volume_provisioner_base_dir | default ('/mnt/disks') }}"
-    mount_dir: "{{ local_volume_provisioner_mount_dir | default('/mnt/disks') }}"
+# Levarages Ansibles string to Python datatype casting. Otherwise the dict_key isn't substituted
+# see https://github.com/ansible/ansible/issues/17324
+local_volume_provisioner_storage_classes: |
+  {
+    "{{ local_volume_provisioner_storage_class | default('local-storage') }}": {
+     "host_dir": "{{ local_volume_provisioner_base_dir | default ('/mnt/disks') }}",
+      "mount_dir": "{{ local_volume_provisioner_mount_dir | default('/mnt/disks') }}"
+    }
+  }
 
 # weave's network password for encryption
 # if null then no network encryption