sched-host-tran: add base interfaces for Scheduled Host Transition

Implement interfaces to get/set scheduledTime and requestedTransition.

Tested:
1. Check scheduledTime
 # busctl get-property xyz.openbmc_project.State.ScheduledHostTransition \
   /xyz/openbmc_project/state/host0 \
   xyz.openbmc_project.State.ScheduledHostTransition ScheduledTime
   t 0
 # busctl set-property xyz.openbmc_project.State.ScheduledHostTransition \
   /xyz/openbmc_project/state/host0 \
   xyz.openbmc_project.State.ScheduledHostTransition ScheduledTime t 1
 # busctl get-property xyz.openbmc_project.State.ScheduledHostTransition \
   /xyz/openbmc_project/state/host0 \
   xyz.openbmc_project.State.ScheduledHostTransition ScheduledTime
   t 1
2. Check requestedTransition
 # busctl get-property xyz.openbmc_project.State.ScheduledHostTransition \
   /xyz/openbmc_project/state/host0 \
   xyz.openbmc_project.State.ScheduledHostTransition RequestedTransition
   s "xyz.openbmc_project.State.Host.Transition.On"
 # busctl set-property xyz.openbmc_project.State.ScheduledHostTransition \
   /xyz/openbmc_project/state/host0 \
   xyz.openbmc_project.State.ScheduledHostTransition RequestedTransition \
   s "xyz.openbmc_project.State.Host.Transition.Off"
 # busctl get-property xyz.openbmc_project.State.ScheduledHostTransition \
   /xyz/openbmc_project/state/host0 \
   xyz.openbmc_project.State.ScheduledHostTransition RequestedTransition
   s "xyz.openbmc_project.State.Host.Transition.Off"

Change-Id: Ie7da8034d37c1069db043772f35982ca821826ae
Signed-off-by: Carol Wang <wangkair@cn.ibm.com>
diff --git a/meson_options.txt b/meson_options.txt
index 0de6b75..443e85c 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -71,3 +71,9 @@
     value: 1,
     description: 'Class version to register with Cereal.',
 )
+
+option(
+    'scheduled-host-transition-busname', type: 'string',
+    value: 'xyz.openbmc_project.State.ScheduledHostTransition',
+    description: 'The scheduled host transition Dbus busname to own.',
+)