refactoring for ansible_module.turbo integration (#313)

* refactoring for ansible_module.turbo integration

This refactoring prepares the integration of `ansible_module.turbo`

- Delay the loading of `common.py`, move the shared structure in
  `args_common`.
- Avoid the use of one single object per module, this to increase the
  amount of Python structure that we can cache.
- Cache the Kubernetes client.

See: https://github.com/ansible-collections/community.kubernetes/pull/270

Co-authored-by: Jill Rouleau <jill.rouleau@bespokess.com>

plugins/inventory/k8s.py

@@ -117,7 +117,7 @@ connections:
 import json
 
 from ansible.errors import AnsibleError
-from ansible_collections.community.kubernetes.plugins.module_utils.common import K8sAnsibleMixin, HAS_K8S_MODULE_HELPER, k8s_import_exception
+from ansible_collections.community.kubernetes.plugins.module_utils.common import K8sAnsibleMixin, HAS_K8S_MODULE_HELPER, k8s_import_exception, get_api_client
 from ansible.plugins.inventory import BaseInventoryPlugin, Constructable, Cacheable
 
 try:
@@ -180,7 +180,7 @@ class InventoryModule(BaseInventoryPlugin, Constructable, Cacheable, K8sAnsibleM
             for connection in connections:
                 if not isinstance(connection, dict):
                     raise K8sInventoryException("Expecting connection to be a dictionary.")
-                client = self.get_api_client(**connection)
+                client = get_api_client(**connection)
                 name = connection.get('name', self.get_default_host_name(client.configuration.host))
                 if connection.get('namespaces'):
                     namespaces = connection['namespaces']
@@ -190,7 +190,7 @@ class InventoryModule(BaseInventoryPlugin, Constructable, Cacheable, K8sAnsibleM
                     self.get_pods_for_namespace(client, name, namespace)
                     self.get_services_for_namespace(client, name, namespace)
         else:
-            client = self.get_api_client()
+            client = get_api_client()
             name = self.get_default_host_name(client.configuration.host)
             namespaces = self.get_available_namespaces(client)
             for namespace in namespaces: