Rawinput messages are not received anymore if the foreground window is
from another process. Using RIDEV_INPUTSINK makes it possible to receive
them again, but with RIM_INPUTSINK flag.

When multiple processes register for rawinput messages, the foreground
process will receive the message, as well as any other that registerd
with RIM_INPUTSINK flag, including when the foreground process itself
did.

Currently the messages may be received correctly, but that depends on
where the input events are generated, so add another test case with
messages sent from the test process, and validate that nothing should
be received.
Signed-off-by: Rémi Bernon <rbernon@codeweavers.com>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>