This PR makes Zed's one-second key binding delay visible.

Say both ctrl-w and ctrl-w left have bindings. After you press ctrl-w,
Zed waits to see whether left follows. The PR shows that wait in the
status bar with a countdown. Hovering the indicator shows which bindings
can still match.

It also adds a setting to hide the indicator. It does not change how Zed
resolves key bindings.

<img height="100" alt="dyn-db84a840272e2f6250a3f527a59b1efd"
src="https://github.com/user-attachments/assets/e42c6a6c-4677-499f-a1d3-835960ebb21a"
/>
<br/>
<img height="100" alt="dyn-8012278d030b41bc8ebfae1540504eff"
src="https://github.com/user-attachments/assets/250928d5-f913-40f0-9068-00ccb5cdf59f"
/>
<br/>
<img height="100" alt="file-5e6ffa90944faa294e7870f471b4e65b"
src="https://github.com/user-attachments/assets/c250e6eb-a269-4e2c-a5a0-0be9b5006f99"
/>

Release Notes:

- Added a status bar countdown for pending multi-stroke key bindings.

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Co-authored-by: Kirill Bulatov <kirill@zed.dev>