Fix various typos

Mainly fix typos in comments, but also some minor code changes:

* Rename `apply_on_poiner` to `apply_on_pointer`.
* Rename `ImeState::Commited` to `ImeState::Committed`
* Correct `cfg_attr` usage: `wayland_platfrom` -> `wayland_platform`.

examples/child_window.rs

@@ -64,7 +64,7 @@ fn main() -> Result<(), impl std::error::Error> {
                     // On x11, println when the cursor entered in a window even if the child window is created
                     // by some key inputs.
                     // the child windows are always placed at (0, 0) with size (200, 200) in the parent window,
-                    // so we also can see this log when we move the cursor arround (200, 200) in parent window.
+                    // so we also can see this log when we move the cursor around (200, 200) in parent window.
                     println!("cursor entered in the window {window_id:?}");
                 }
                 WindowEvent::KeyboardInput {