keymap: Update `Prev` to `Previous` follow-up (#25931)

Follow-up for https://github.com/zed-industries/zed/pull/25909

Add three more action replacements:

```
1. "pane::ActivatePrevItem" -> "pane::ActivatePreviousItem"
2. "vim::MoveToPrev" -> "vim::MoveToPrevious"
3. "vim:MoveToPrevMatch" -> "vim:MoveToPreviousMatch" 
```

Release Notes:

- N/A