Add systemd service file

:Release Notes:
This patch is adding the systemd service file

:Detailed Notes:
This patch installs systemd related files.
It includes systemd service file and script file, occasionally.
The files would be installed at /etc/systemd/system

Wiki page regarding decentralize systemd files:
https://wiki.lgsvl.com/display/webOSDocs/Decentralize+systemd+files

:Testing Performed:
Build ok, The files are installed at /etc/systemd/system

:QA Notes:

:Issues Addressed:
[PLAT-68059] Decentralize systemd units to each component #2

Change-Id: I50b7cd6a451500711b1685888dd31fc746fd1e24
Reviewed-on: http://gpro.lgsvl.com/225887
Reviewed-by: Eunmin Lim <[email protected]>
Reviewed-by: Sukil Hong <[email protected]>
Reviewed-by: Sangwoo Kang <[email protected]>
Tested-by: Sangwoo Kang <[email protected]>

files/launch/activitymanager.service.in

@@ -0,0 +1,31 @@
+# Copyright (c) 2019 LG Electronics, Inc.
+#
+# 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.
+#
+# SPDX-License-Identifier: Apache-2.0
+
+# Open webOS component to manage all running activities.
+
+[Unit]
+Description=default - "%n"
+Requires=ls-hubd.service configurator-db8.service
+After=ls-hubd.service configurator-db8.service
+Wants=configurator-activity.service
+Before=configurator-activity.service
+
+[Service]
+Type=notify
+OOMScoreAdjust=-500
+EnvironmentFile=-/var/systemd/system/env/activitymanager.env
+ExecStart=/usr/sbin/activitymanager -c {\"log\":{\"appender\":{\"type\":\"syslog\"},\"levels\":{\"default\":\"notice\"}}}
+Restart=on-failure