Merge lcm.yang file from APP-C to CCSDK

These are all the differences found in yang level in both the projects.

1. An addition parameter called payload in output of rpc defintion of appc-provider-lcm.yang for UpgradePostCheck, health-check and UpgradePreCheck is present. The same payload parameter was added to the ccsdk-sli-northbound project's lcm.yang file for rpc defintion of UpgradePostCheck, health-check and UpgradePreCheck.
       

output {
            uses common-header;
            uses status;
            leaf payload {
                type payload;
                mandatory true;
                         }
        }

2. In config-scale-out of appc-provider-lcm.yang input payload is mandatory whereas in ccsdk-sli-northbound project's lcm.yang it is optional. It has been changed to "mandatory true" to match the appc-provider-lcm.yang from the appc project.