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_impl/linux/x11/ime/input_method.rs

@@ -170,7 +170,7 @@ impl From<util::GetPropertyError> for GetXimServersError {
     }
 }
 
-// The root window has a property named XIM_SERVERS, which contains a list of atoms represeting
+// The root window has a property named XIM_SERVERS, which contains a list of atoms representing
 // the availabile XIM servers. For instance, if you're using ibus, it would contain an atom named
 // "@server=ibus". It's possible for this property to contain multiple atoms, though presumably
 // rare. Note that we replace "@server=" with "@im=" in order to match the format of locale