vim: Fix escape key switching back to default mode instead of normal mode (#31843)

Closes #31728

This PR introduced new setting `"helix_mode"`. Enabling which will
enable the `vim_mode` along with `helix` behavior.

This solves issue where `vim`'s `default_mode` was being used to switch
between mode instead of opening in `default_mode`.

When `helix_mode` is enabled switcing to `Normal mode` will now switch
to `HelixNormal`


Release Notes:

- Fixed - escape key not switching to normal mode when default_mode is
insert
- Added - `helix_mode` setting to enable/disable helix key bindings

---------

Co-authored-by: Conrad Irwin <conrad.irwin@gmail.com>

assets/settings/default.json

@@ -110,6 +110,8 @@
   "multi_cursor_modifier": "alt",
   // Whether to enable vim modes and key bindings.
   "vim_mode": false,
+  // Whether to enable helix mode and key bindings.
+  "helix_mode": false,
   // Whether to show the informational hover box when moving the mouse
   // over symbols in the editor.
   "hover_popover_enabled": true,