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

assets/keymaps/default-macos.json

@@ -355,8 +355,8 @@
     "context": "Pane",
     "use_key_equivalents": true,
     "bindings": {
-      "alt-cmd-left": "pane::ActivatePrevItem",
-      "cmd-{": "pane::ActivatePrevItem",
+      "alt-cmd-left": "pane::ActivatePreviousItem",
+      "cmd-{": "pane::ActivatePreviousItem",
       "alt-cmd-right": "pane::ActivateNextItem",
       "cmd-}": "pane::ActivateNextItem",
       "ctrl-shift-pageup": "pane::SwapItemLeft",