Add subscription_id to Lti::ToolProxy

refs PLAT-5765
flag=none

Test plan
- N/A

Change-Id: Ie00a8d0feaa1193ee2a4c46aa5c72c9b781fb45d
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/240278
Reviewed-by: Cody Cutrer <cody@instructure.com>
QA-Review: Cody Cutrer <cody@instructure.com>
Product-Review: Cody Cutrer <cody@instructure.com>
Tested-by: Service Cloud Jenkins <svc.cloudjenkins@instructure.com>

db/migrate/20200528232129_add_subscription_id_to_lti_tool_proxy.rb

@@ -0,0 +1,29 @@
+#
+# Copyright (C) 2020 - present Instructure, Inc.
+#
+# This file is part of Canvas.
+#
+# Canvas is free software: you can redistribute it and/or modify it under
+# the terms of the GNU Affero General Public License as published by the Free
+# Software Foundation, version 3 of the License.
+#
+# Canvas is distributed in the hope that it will be useful, but WITHOUT ANY
+# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+# A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
+# details.
+#
+# You should have received a copy of the GNU Affero General Public License along
+# with this program. If not, see <http://www.gnu.org/licenses/>.
+#
+class AddSubscriptionIdToLtiToolProxy < ActiveRecord::Migration[5.2]
+
+  tag :predeploy
+
+  def up
+    add_column :lti_tool_proxies, :subscription_id, :string
+  end
+
+  def down
+    remove_column :lti_tool_proxies, :subscription_id, :string
+  end
+end