Rename from community.kubernetes to kubernetes.core (#6)

* Rename from community.kubernetes to kubernetes.core

This goes through and renames community.kubernetes to kubernetes.core.
Most of this was generated from the downstream build script that was
used on the community repository, plus whatever hand edits I could find
that were needed.

The downstream build and test process has also been removed as this
repository is now the downstream repository.

* Fix CONTRIBUTING.md

plugins/modules/k8s_exec.py

@@ -23,7 +23,7 @@ description:
   - Use the Kubernetes Python client to execute command on K8s pods.
 
 extends_documentation_fragment:
-  - community.kubernetes.k8s_auth_options
+  - kubernetes.core.k8s_auth_options
 
 requirements:
   - "python >= 2.7"
@@ -66,13 +66,13 @@ options:
 
 EXAMPLES = r'''
 - name: Execute a command
-  community.kubernetes.k8s_exec:
+  kubernetes.core.k8s_exec:
     namespace: myproject
     pod: zuul-scheduler
     command: zuul-scheduler full-reconfigure
 
 - name: Check RC status of command executed
-  community.kubernetes.k8s_exec:
+  kubernetes.core.k8s_exec:
     namespace: myproject
     pod: busybox-test
     command: cmd_with_non_zero_exit_code
@@ -118,9 +118,9 @@ except ImportError:
     # ImportError are managed by the common module already.
     pass
 
-from ansible_collections.community.kubernetes.plugins.module_utils.ansiblemodule import AnsibleModule
+from ansible_collections.kubernetes.core.plugins.module_utils.ansiblemodule import AnsibleModule
 from ansible.module_utils._text import to_native
-from ansible_collections.community.kubernetes.plugins.module_utils.common import (
+from ansible_collections.kubernetes.core.plugins.module_utils.common import (
     AUTH_ARG_SPEC
 )
 
@@ -192,7 +192,7 @@ def main():
         argument_spec=argspec(),
         supports_check_mode=True,
     )
-    from ansible_collections.community.kubernetes.plugins.module_utils.common import (
+    from ansible_collections.kubernetes.core.plugins.module_utils.common import (
         K8sAnsibleMixin, get_api_client)
 
     k8s_ansible_mixin = K8sAnsibleMixin(module)