Modernize feresectl and add bounded IPC event streaming

scripts/tests/test_floating_placement_isolated.py

@@ -68,7 +68,7 @@ class FloatingPlacementTest(unittest.TestCase):
                 return child
 
             def command(*args):
-                return json.loads(subprocess.check_output([str(repo / "target/debug/feresectl"), *args], env=env, timeout=5))
+                return json.loads(subprocess.check_output([str(repo / "target/debug/feresectl"), "-j", *args], env=env, timeout=5))
 
             with (root / "compositor.log").open("w") as log:
                 try: