vim: Show 'j' from jk pre-emptively (#32007)

Fixes: #29812
Fixes: #22538

Co-Authored-By: <corentinhenry@gmail.com>

Release Notes:

- vim: Multi-key bindings in insert mode will now show the pending
keystroke in the buffer. For example if you have `jk` mapped to escape,
pressing `j` will immediately show a `j`.

crates/gpui/src/platform.rs

@@ -839,7 +839,7 @@ impl PlatformInputHandler {
             .ok();
     }
 
-    fn replace_and_mark_text_in_range(
+    pub fn replace_and_mark_text_in_range(
         &mut self,
         range_utf16: Option<Range<usize>>,
         new_text: &str,

crates/gpui/src/window.rs

@@ -3542,6 +3542,7 @@ impl Window {
                         .dispatch_tree
                         .flush_dispatch(currently_pending.keystrokes, &dispatch_path);
 
+                    window.pending_input_changed(cx);
                     window.replay_pending_input(to_replay, cx)
                 })
                 .log_err();