Add test definition to install tests cases

Signed-off-by: Luis Araujo <luis.araujo@collabora.co.uk>

install-tests-cases.yaml

+metadata:
+  name: install-tests-cases
+  format: "Lava Test Definition 1.0"
+  description: "Install test cases"
+
+run:
+  steps:
+    - lava-test-case create-tests-cases-dir --shell mkdir -R /var/lib/tests_cases/
+    - lava-test-case install-tests-cases --shell cp tc/* /var/lib/tests_cases/