Implement group membership in compute-vm module (#3816)

* implement group membership in compute-vm module

* fix newline, update copyright

tests/modules/compute_vm/examples/group-membership.yaml

@@ -0,0 +1,26 @@
+# Copyright 2026 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+values:
+  module.instance-group-membership.google_compute_instance.default[0]: {}
+  module.instance-group-membership.google_compute_instance_group_membership.unmanaged[0]:
+    instance_group: my-existing-group-id
+    project: project-id
+    timeouts: null
+    zone: europe-west8-b
+
+counts:
+  google_compute_instance: 1
+  google_compute_instance_group_membership: 1
+