tests: Convert keyboard-test to new test extension

This adds a weston-test-runner for the weston test extension and
some weston test client helper methods.

Converted keyboard-test to use the new test interface, runner,
and helper methods.

Fixes https://bugs.freedesktop.org/show_bug.cgi?id=56822

Signed-off-by: U. Artie Eoff <ullysses.a.eoff@intel.com>

tests/.gitignore

@@ -5,3 +5,4 @@ test-text-client
 wayland-test-client-protocol.h
 wayland-test-protocol.c
 wayland-test-server-protocol.h
+keyboard-test