DetailedList refresh view can't be activated on macOS 14 (Sonoma)

### Describe the bug

When using macOS Sonoma, the DetailedList "pull to refresh" behavior can't be activated.

### Steps to reproduce

1. Run the `DetailedList` example app
2. Try to pull down to refresh the data.

The scroll view won't "bounce" allowing the view to be refreshed.

### Expected behavior

It should be possible to invoke refresh.

### Screenshots

_No response_

### Environment

- Operating System: macOS Sonoma
- Python version: All? (tested on 3.10)
- Software versions:
- Toga: 0.4.2

### Logs

_No response_

### Additional context

The underlying problem appears to be that scroll elasticity has been disabled in Sonoma. On my test machine, there's no "bounce" on *any* scroll container if you try to scroll past the limits of the window. Toga-demo is enough to demonstrate this - on Ventura, there's a bounce; on my clean Sonoma install, there isn't.

This came up in testing of #2404 - there's a FIXME in cocoa/widgets/internals/refresh.py:103 that disables code coverage on the branch that would be triggered by a working pull-to-scroll implementation.

However, it appears that pull-to-scroll hasn't been *universally* disabled - I've checked with someone else who has a Sonoma install, and they *do* have elasticity in their scroll views.

To fix this - we should add a "refresh" option to the context menu where actions are displayed

Start with cocoa/widgets/internals/refresh.py, especially the FIXME around line 103, and reproduce the DetailedList example on macOS Sonoma. Compare the refresh behavior with the available context-menu actions and verify that users can invoke refresh even when scroll elasticity is unavailable.

Written by the indexing model from the issue text.