Update placeholder text with key bindings to focus context panel and navigate history (#19447)

Hopefully, this will help people understand how easy it is to add
context to an inline transformation.

![CleanShot 2024-10-18 at 22 41
00@2x](https://github.com/user-attachments/assets/c09c1d89-3df2-4079-9849-9de7ac63c003)

@as-cii @maxdeviant @rtfeldman could somebody update this to display the
actual correct key bindings and ship it. I have them hard coded for now.

Release Notes:

- Updated placeholder text with key bindings to focus context panel and
navigate history.

---------

Co-authored-by: Richard Feldman <oss@rtfeldman.com>

crates/ui/src/components/keybinding.rs

@@ -196,7 +196,7 @@ impl KeyIcon {
 }
 
 /// Returns a textual representation of the key binding for the given [`Action`].
-pub fn text_for_action(action: &dyn Action, cx: &mut WindowContext) -> Option<String> {
+pub fn text_for_action(action: &dyn Action, cx: &WindowContext) -> Option<String> {
     let key_binding = cx.bindings_for_action(action).last().cloned()?;
     Some(text_for_key_binding(key_binding, PlatformStyle::platform()))
 }