[Application][Linux] Convert tools to C++

We don't have strong reasons to keep them a C, so to keep consistency
and make use of our lint checks, moving those to C++.

We still use gdbus here (instead of src/dbus) due to it's convenient
sync API (for the case of the tools, this API is OK) and to avoid
needing to integrate appcore/aul with base::MessageLoop.
[Application][Linux] Convert xwalk_launcher_tizen.c to C++

Missed from last change. Also should fix build break in Tizen build.
[Tizen] Fix coding style error
[Tizen] Change MouseDown method

Mouse down event in Elementary Plug don't send it's coordinates, it gets
from the last mouse move. We changed the MouseDown method to trigger the
MouseMove method before.

The dropdown in TizenSystemIndicator landscape mode needs the
last coordinates to succeed.