First pass at getting new UI testing down

[tsmartt]

Resolves https://github.com/brave-intl/creators-private-issues/issues/1859

For now we have to run next separately to run the tests, eventually we want capybara to launch next and run the tests.

At least locally, this gets

bin/rails test test/features/publishers_home_test.rb:28

working. The shadowdom is tricky to work with, so we might want to revisit that in the future.