windows: Show alt-= for pane::GoForward (#38696)

Reorder the shortcuts for `pane::GoForward` so the menu now shows
`Alt-=` instead of `forward`

Release Notes:

- N/A

assets/keymaps/default-windows.json

@@ -465,8 +465,8 @@
       "ctrl-k ctrl-w": "workspace::CloseAllItemsAndPanes",
       "back": "pane::GoBack",
       "alt--": "pane::GoBack",
-      "alt-=": "pane::GoForward",
       "forward": "pane::GoForward",
+      "alt-=": "pane::GoForward",
       "f3": "search::SelectNextMatch",
       "shift-f3": "search::SelectPreviousMatch",
       "ctrl-shift-f": "project_search::ToggleFocus",