Support Vite in feature tests

What does this MR do and why?

This MR adds Vite support for running feature tests locally.

See also the complementary GDK MR: gitlab-development-kit!3448 (merged)

How to set up and validate locally

1. Run echo "Feature.enable(:vite)" | gdk rails c
2. Launch bundle exec vite dev
3. Restart GDK
4. Run gdk stop webpack
5. Run any feature spec, example: spec/features/merge_request/user_approves_spec.rb
6. Verify it runs successfully