ui/curses: add curses interface draft

pqcli/ui/curses/event_handler.py

@@ -0,0 +1,14 @@
+import typing as T
+
+
+class EventHandler:
+    def __init__(self) -> None:
+        self.callbacks: T.List[T.Callable[..., T.Any]] = []
+
+    def __call__(self, *args: T.Any, **kwargs: T.Any) -> None:
+        for callback in self.callbacks:
+            callback(*args, **kwargs)
+
+    def __iadd__(self, callback: T.Callable[..., T.Any]) -> "EventHandler":
+        self.callbacks.append(callback)
+        return self