change(mac): improve on-screen keyboard menu item

### Describe the bug

The menu item 'On-Screen Keyboard' should be renamed to 'Show On-Screen Keyboard' when the OSK is currently hidden. When the OSK is shown, then the menu should automatically rename to 'Hide On-Screen Keyboard'

This means the menu is changing from only being able to show the OSK to toggling its shown/hidden state.

### Reproduce the bug

_No response_

### Expected behavior

_No response_

### Related issues

_No response_

### Keyman apps

- [ ] Keyman for Android
- [ ] Keyman for iPhone and iPad
- [ ] Keyman for Linux
- [X] Keyman for macOS
- [ ] Keyman for Windows
- [ ] Keyman Developer
- [ ] KeymanWeb
- [ ] Other - give details at bottom of form

### Keyman version

_No response_

### Operating system

_No response_

### Device

_No response_

### Target application

_No response_

### Browser

_No response_

### Keyboard name

_No response_

### Keyboard version

_No response_

### Language name

_No response_

### Additional context

_No response_