cros-ec.yaml: Add Lava-Test Test Definition 1.0

Add a Lava-Test Definition to be able to run the test suite in the LAVA
dispatcher using lqa.
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>

cros-ec.yaml

+metadata:
+  name: cros-ec
+  description: "cros-ec test plan"
+  environment:
+    - lava-test-shell
+
+run:
+  steps:
+    - python3 $(pwd)/test-cros-ec.py