Doc fragments to plugins (#50172)

* promote doc_fragments into actual plugins

  change tests hardcoded path to doc fragments
  avoid sanity in fragments
  avoid improper testing of doc_fragments
  also change runner paths
 fix botmeta
 updated comment for fragments
 updated docs

lib/ansible/plugins/doc_fragments/gcp.py

@@ -0,0 +1,40 @@
+# Copyright: (c) 2018, Google Inc.
+# GNU General Public License v3.0+ (see COPYING or https://www.gnu.org/licenses/gpl-3.0.txt)
+
+
+class ModuleDocFragment(object):
+        # GCP doc fragment.
+        DOCUMENTATION = '''
+options:
+    project:
+        description:
+            - The Google Cloud Platform project to use.
+        default: null
+    auth_kind:
+        description:
+            - The type of credential used.
+        required: true
+        choices: ["machineaccount", "serviceaccount", "application"]
+    service_account_file:
+        description:
+            - The path of a Service Account JSON file if serviceaccount is selected as type.
+    service_account_email:
+        description:
+            - An optional service account email address if machineaccount is selected
+              and the user does not wish to use the default email.
+    scopes:
+      description:
+          - Array of scopes to be used.
+notes:
+  - For authentication, you can set service_account_file using the
+    C(GCP_SERVICE_ACCOUNT_FILE) env variable.
+  - For authentication, you can set service_account_email using the
+    C(GCP_SERVICE_ACCOUNT_EMAIL) env variable.
+  - For authentication, you can set auth_kind using the C(GCP_AUTH_KIND) env
+    variable.
+  - For authentication, you can set scopes using the C(GCP_SCOPES) env variable.
+  - Environment variables values will only be used if the playbook values are
+    not set.
+  - The I(service_account_email) and I(service_account_file) options are
+    mutually exclusive.
+'''