Revert "Hide the mouse when the user is typing in the editor (#25040)" (#25393)

This reverts commit a8610fbd13.

I've been seeing some reports of segmentation faults that appear to
point to this change as the culprit.

Closes #25366.

Release Notes:

- Community: Reverted #25040, so remove the corresponding entry from the
release notes.

crates/gpui/src/platform.rs

@@ -1227,9 +1227,6 @@ pub enum CursorStyle {
     /// A cursor indicating that the operation will result in a context menu
     /// corresponds to the CSS cursor value `context-menu`
     ContextualMenu,
-
-    /// Hide the cursor
-    None,
 }
 
 impl Default for CursorStyle {