KWin in plasma/kwin@ef72bae42f removed the libinput
option, if we start kwin with this option, it fails with unknown option
libinput and eventually gives up
Instead of relying on an environment variable
This will also set the other necessary settings that we need for the
session to integrate properly like the Placement strategy for kwin
I wonder why we were specifying maliit-server now, definitely was
unused.
Using maliit-keyboard we'll get to leverage the input-method-v1 support
we have now in kwin, allowing to move the keyboard into a separate
process and making the development of the virtual keyboard increasinly
modular.
