[Application] Allow passing the NET_WM_PID as a LaunchParam

In Tizen, the windows of applications launched in service mode should
have their X11 property NET_WM_PID set to the launcher PID, so that the
task manager can find the right X11 window associated with each
application launched.

This commit prepares the ground, a separate patch will actually get the
PID information and set the launcher_pid parameter.
Merge pull request #1529 from cmarcelo/net-wm-pid-launch-param

[Application] Allow passing the NET_WM_PID as a LaunchParam