Add a way to navigate between changes (#28891)

Closes https://github.com/zed-industries/zed/issues/19731

Adds `editor::GoToPreviousChange` and `editor::GoToNextChange` that work
the same as `vim::ChangeListOlder` and `vim::ChangeListNewer` as the
common logic was extracted and reused.

Release Notes:

- Added a way to navigate between changes with
`editor::GoToPreviousChange` and `editor::GoToNextChange`

assets/keymaps/default-linux.json

@@ -134,7 +134,9 @@
       "shift-f10": "editor::OpenContextMenu",
       "ctrl-shift-e": "editor::ToggleEditPrediction",
       "f9": "editor::ToggleBreakpoint",
-      "shift-f9": "editor::EditLogBreakpoint"
+      "shift-f9": "editor::EditLogBreakpoint",
+      "ctrl-shift-backspace": "editor::GoToPreviousChange",
+      "ctrl-shift-alt-backspace": "editor::GoToNextChange"
     }
   },
   {