Display case-sensitive keybindings for vim commands (#24322)

This Pull Request tackles the issue outline in #14287 by changing the
way `KeyBinding`s for vim mode are displayed in the command palette.
It's worth pointing out that this whole thing was pretty much
implemented by Conrad Irwin during a pairing session, I just tried to
clean up some other changes introduced for a different issue, while
improving some comments.

Here's a quick list of the changes introduced:

- Update `KeyBinding` with a new `vim_mode` field to determine whether
the keybinding should be displayed in vim mode.
- Update the way `KeyBinding` is rendered, so as to detect if the
keybinding is for vim mode, if it is, only display keys in uppercase if
they require the shift key.
- Introduce a new global state – `VimStyle(bool)` - use to determine
whether `vim_mode` should be enabled or disabled when creating a new
`KeyBinding` struct. This global state is automatically set by the `vim`
crate whenever vim mode is enabled or disabled.
- Since the app's context is now required when building a `KeyBinding` ,
update a lot of callers to correctly pass this context.

And before and after screenshots, for comparison:

| before | after |
|--------|-------|
| <img width="1050" alt="SCR-20250205-tyeq"
src="https://github.com/user-attachments/assets/e577206d-2a3d-4e06-a96f-a98899cc15c0"
/> | <img width="1050" alt="SCR-20250205-tylh"
src="https://github.com/user-attachments/assets/ebbf70a9-e838-4d32-aee5-0ffde94d65fb"
/> |

Closes #14287 

Release Notes:

- Fix rendering of vim commands to preserve case sensitivity

---------

Co-authored-by: Conrad Irwin <conrad.irwin@gmail.com>

crates/assistant/src/terminal_inline_assistant.rs

@@ -725,7 +725,7 @@ impl PromptEditor {
                 cx,
             );
             editor.set_soft_wrap_mode(language::language_settings::SoftWrap::EditorWidth, cx);
-            editor.set_placeholder_text(Self::placeholder_text(window), cx);
+            editor.set_placeholder_text(Self::placeholder_text(window, cx), cx);
             editor
         });
 
@@ -774,8 +774,8 @@ impl PromptEditor {
         this
     }
 
-    fn placeholder_text(window: &Window) -> String {
-        let context_keybinding = text_for_action(&zed_actions::assistant::ToggleFocus, window)
+    fn placeholder_text(window: &Window, cx: &App) -> String {
+        let context_keybinding = text_for_action(&zed_actions::assistant::ToggleFocus, window, cx)
             .map(|keybinding| format!(" • {keybinding} for context"))
             .unwrap_or_default();