homescreen: Change from qmake to meson

homescreen: Change from qmake to meson

This change will basically make way for adding grpc/protobuf support
into homescreen, which turns out it's a pain to do with either qmake or
cmake. Eventually, we'll move all our demos to using meson, which have
gained a lot of support for building and support different technologies
to allow far more saner configurations to take place.

Based heavily on the work done by Scott Murray in libqtappfw,
in the applauncher module.

Bug-AGL: SPEC-4584
Signed-off-by: Marius Vlad <marius.vlad@collabora.com>
Suggested-by: Scott Murray <scott.murray@konsulko.com>
Change-Id: Id64bf3d5b41912d32df7f78e94ab04d231bb0c83