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`.

src/platform/scancode.rs

@@ -9,7 +9,7 @@ use crate::keyboard::{KeyCode, PhysicalKey};
 pub trait PhysicalKeyExtScancode {
     /// The raw value of the platform-specific physical key identifier.
     ///
-    /// Returns `Some(key_id)` if the conversion was succesful; returns `None` otherwise.
+    /// Returns `Some(key_id)` if the conversion was successful; returns `None` otherwise.
     ///
     /// ## Platform-specific
     /// - **Windows:** A 16bit extended scancode