Implement StopObject()

For some test cases, we might want to stop a service earlier. This
functionality is done by StopObject().

Test log collection is still done by UndeployObject(), which will
collect the logs of all services (at that point, stopped or not).

ci-scripts/tests/simple-undep/docker-compose.yml

@@ -0,0 +1,23 @@
+services:
+  testA:
+    image: ubuntu:${TAG:-jammy}
+    container_name: test_container_A
+    cap_drop:
+      - ALL
+    entrypoint: /bin/bash -c "sleep infinity"
+    healthcheck:
+      test: /bin/bash -c "true"
+      interval: 1s
+      timeout: 1s
+      retries: 1
+  testB:
+    image: ubuntu:${TAG:-jammy}
+    container_name: test_container_B
+    cap_drop:
+      - ALL
+    entrypoint: /bin/bash -c "sleep infinity"
+    healthcheck:
+      test: /bin/bash -c "true"
+      interval: 1s
+      timeout: 1s
+      retries: 1