protocol: add interface ivi_application extension

protocol: add interface ivi_application extension

- introduces ivi-application.xml

Many applications in an IVI-system are special single-purpose
applications that have a very specific role in the whole IVI UI, for
example a rear camera, speedometer, map, etc. The IVI system vendor
specifies what these are and how they integrate into the UI. They also
vary between particular IVI systems. This is why we use (system-)global,
unique, pre-determined ID numbers to tell what wl_surface is which
application, instead of writing specific shell requests for each one.
Using ID numbers allows vendors to easily invent new component
applications without extending or breaking the actual Wayland protocol.
In IVI-systems, the ID is a standard concept already used in several
APIs, with a vendor-specified global definition of ID assignments.

Signed-off-by: Nobuhiko Tanibata <NOBUHIKO_TANIBATA@xddp.denso.co.jp>
Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>