Add COMPUTE_EPHEMERAL_ENCRYPTION tratis

This includes format specific traits under
COMPUTE_EPEHEMERAL_ENCRYPTION_$FORMAT.

Change-Id: I0438e39a3c61253f781761a5aae895993f897adb

os_traits/compute/ephemeral.py

@@ -0,0 +1,20 @@
+# -*- coding: utf-8 -*-
+
+# 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.
+
+TRAITS = [
+    'ENCRYPTION',
+    'ENCRYPTION_PLAIN',
+    'ENCRYPTION_LUKS',
+    'ENCRYPTION_LUKSV2',
+]