helix: Stay in helix normal mode after helix delete (#34093)

Currently, the HelixDelete action switches to (vim) Normal mode instead
of HelixNormal mode. This adds a line to the helix delete action to stay
in helix normal mode.

There was already a commented-out test for this. I've uncommented it and
it now passes.

Release Notes:

- helix: Fixed switching to vim NORMAL mode instead of HELIX_NORMAL mode
after deletion

crates/vim/src/normal.rs

@@ -140,6 +140,7 @@ pub(crate) fn register(editor: &mut Editor, cx: &mut Context<Vim>) {
             })
         });
         vim.visual_delete(false, window, cx);
+        vim.switch_mode(Mode::HelixNormal, true, window, cx);
     });
 
     Vim::action(editor, cx, |vim, _: &ChangeToEndOfLine, window, cx| {