The `ToggleInlineValues` action was added when inline value hints were
introduced, but the action was never registered, so it was not
dispatchable: it never appeared in the command palette and any
keybinding bound to it had no effect.

Follow-up to #28656.

Self-Review Checklist:

- [x] I've reviewed my own diff for quality, security, and reliability
- [ ] Unsafe blocks (if any) have justifying comments
- [ ] The content adheres to Zed's UI standards
([UX/UI](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)
and
[icon](https://github.com/zed-industries/zed/blob/main/crates/icons/README.md)
guidelines)
- [ ] Tests cover the new/changed behavior
- [ ] Performance impact has been considered and is acceptable

Closes #58890.

Release Notes:

- Fixed “editor: toggle inline values” not appearing in the command
palette or responding to keybindings