Modernize feresectl and add bounded IPC event streaming

scripts/tests/test_focus_history_isolated.py

@@ -40,7 +40,7 @@ class FocusHistoryTest(unittest.TestCase):
 
             def command(*args):
                 return json.loads(subprocess.check_output(
-                    [str(repo / "target/debug/feresectl"), *args], env=env, timeout=5
+                    [str(repo / "target/debug/feresectl"), "-j", *args], env=env, timeout=5
                 ))
 
             def wait_for(predicate):