clan-cli: Replace HostGroup and MachineGroup with generic AsyncRuntime class. Propagate cmd prefix over thread local. Close threads on CTRL+C

pkgs/clan-cli/tests/runtime.py

@@ -0,0 +1,7 @@
+import pytest
+from clan_cli.async_run import AsyncRuntime
+
+
+@pytest.fixture
+def runtime() -> AsyncRuntime:
+    return AsyncRuntime()