debugger: Add keyboard navigation for breakpoint list (#31221)

Release Notes:

- Debugger Beta: made it possible to navigate the breakpoint list using
menu keybindings.

crates/zed_actions/src/lib.rs

@@ -339,3 +339,5 @@ pub mod outline {
 
 actions!(zed_predict_onboarding, [OpenZedPredictOnboarding]);
 actions!(git_onboarding, [OpenGitIntegrationOnboarding]);
+
+actions!(debugger, [ToggleEnableBreakpoint, UnsetBreakpoint]);