Move DataTable cursor with page up/down, home, end (#2228)

* Add pageup and pagedown actions to DataTable, with no impls

* Pagedown moves DataTable cursor now

* Account for header height in pagedown action

* Page Up support in the DataTable

* Fix and off-by-1, ensure page up/down works on col cursor

* Add placeholder scroll home/end action handlers to datatable

* Add scroll home and scroll end

* Hide hover cursor when home or end is used

* Ensure home and end work correctly with all curosrs

* Testing home/end/pagedown/pageup cursor movement in DataTable

* Docstrings for new datatable actions

* Fix a broken unit test for the DataTable

tests/test_data_table.py

@@ -167,10 +167,36 @@ async def test_datatable_message_emission():
 async def test_empty_table_interactions():
     app = DataTableApp()
     async with app.run_test() as pilot:
-        await pilot.press("enter", "up", "down", "left", "right")
+        await pilot.press(
+            "enter", "up", "down", "left", "right", "home", "end", "pagedown", "pageup"
+        )
         assert app.message_names == []
 
 
+async def test_cursor_movement_with_home_pagedown_etc():
+    app = DataTableApp()
+
+    async with app.run_test() as pilot:
+        table = app.query_one(DataTable)
+        table.add_columns("A", "B")
+        table.add_rows(ROWS)
+        await pilot.press("right", "pagedown")
+        await pilot.pause()
+        assert table.cursor_coordinate == Coordinate(2, 1)
+
+        await pilot.press("pageup")
+        await pilot.pause()
+        assert table.cursor_coordinate == Coordinate(0, 1)
+
+        await pilot.press("end")
+        await pilot.pause()
+        assert table.cursor_coordinate == Coordinate(2, 1)
+
+        await pilot.press("home")
+        await pilot.pause()
+        assert table.cursor_coordinate == Coordinate(0, 1)
+
+
 async def test_add_rows():
     app = DataTableApp()
     async with app.run_test():