tests: Rename wayland-test to weston-test

tests: Rename wayland-test to weston-test

wayland-test isn't and will never be wayland protocol, it's weston internal.

Renamed wayland-test to weston-test, and wl_test to weston_test.

Also added a Big Fat Warning to the description of weston_test to try to
keep people from thinking it's a good idea to use some of these functions
outside of testing.

Signed-off-by: Derek Foreman <derekf@osg.samsung.com>
Acked-by: Bryce Harrington <bryce@osg.samsung.com>
Reviewed-by: Bryce Harrington <bryce@osg.samsung.com>