Add a test for a screen binding movement, wrapping a focusable widget

This is the heart of the issue introduced by
b48a1402b8
and which is being investigated in
https://github.com/Textualize/textual/issues/1343 -- the child widget can be
focused, but (as far as the author of the code is concerned) it has no
bindings. Bindings for movement-oriented keys exist on the screen which
composes up the widget into it. Up until 0.5.0 this worked just fine. As of
0.6.0, because binding inheritance was introduced, the bindings for movement
that live at the `Widget` level cause the widget that has no bindings to
appear to have bindings.

While this can potentially be worked around with the use of
inherit_bindings, this isn't a very satisfying solution and also breaks the
rule of least astonishment.

This test is going to be key to all of this. This is the test that should be
made to work without breaking any of the other currently-passing tests.

tests/test_binding_inheritance.py

@@ -164,3 +164,42 @@ async def test_focused_child_widget_with_movement_bindings() -> None:
     async with AppWithWidgetWithBindings().run_test() as pilot:
         await pilot.press("x", *MOVEMENT_KEYS, "x")
         assert pilot.app.pressed_keys == ["x", *[f"locally_{key}" for key in MOVEMENT_KEYS], "x"]
+
+##############################################################################
+class FocusableWidgetWithNoBindings(Static, can_focus=True):
+    """A widget that can receive focus but has no bindings."""
+
+class ScreenWithMovementBindings(Screen):
+    """A screen that binds keys, including movement keys."""
+
+    BINDINGS = [
+        Binding("x", "record('x')", "x"),
+        *[Binding(key, f"screen_record('{key}')", key) for key in MOVEMENT_KEYS]
+    ]
+
+    async def action_screen_record(self, key: str) -> None:
+        # Sneaky forward reference. Just for the purposes of testing.
+        await self.app.action_record(f"screen_{key}")
+
+    def compose(self) -> ComposeResult:
+        yield FocusableWidgetWithNoBindings()
+
+    def on_mount(self) -> None:
+        self.query_one(FocusableWidgetWithNoBindings).focus()
+
+class AppWithScreenWithBindingsWidgetNoBindings(AppKeyRecorder):
+    """An app with a non-default screen that handles movement key bindings."""
+
+    SCREENS = {"main":ScreenWithMovementBindings}
+
+    def on_mount(self) -> None:
+        self.push_screen("main")
+
+@pytest.mark.xfail(
+    reason="Movement keys never make it to the screen with such bindings due to key inheritance and pre-bound movement keys [issue#1343]"
+)
+async def test_focused_child_widget_with_movement_bindings_on_screen() -> None:
+    """A focused child widget, with movement bindings in the screen, should trigger screen actions."""
+    async with AppWithScreenWithBindingsWidgetNoBindings().run_test() as pilot:
+        await pilot.press("x", *MOVEMENT_KEYS, "x")
+        assert pilot.app.pressed_keys == ["x", *[f"locally_{key}" for key in MOVEMENT_KEYS], "x"]