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`

crates/editor/src/actions.rs

@@ -306,6 +306,8 @@ actions!(
         GoToPreviousHunk,
         GoToImplementation,
         GoToImplementationSplit,
+        GoToNextChange,
+        GoToPreviousChange,
         GoToPreviousDiagnostic,
         GoToTypeDefinition,
         GoToTypeDefinitionSplit,