Add login_hint to permitted params

[Roriz]

As a aplication send username/email to auth0 universal login page. Auth0 already have feature to autofil username/email if has been sended.

Changes

Add login_hint on allow list of params of authorize_params

References

https://auth0.com/docs/universal-login/new-experience#login

Testing

• This change adds unit test coverage
• This change has been tested on the latest version of the platform/language or why not

Checklist

• I have read the Auth0 contribution guidelines
• I have read the Auth0 Code of Conduct
• All existing and new tests complete without errors
• All code quality tools/guidelines in the CONTRIBUTING documentation have been run/followed

Workaround

config/initializers/auth0.rb

Rails.application.config.middleware.use OmniAuth::Builder do
  options({
    login_hint: lambda do |env|
      Rack::Utils.parse_query(env['rack.input'].gets)['login_hint']
    end
  })

  provider(
    :auth0,
    auth0_client_id
    auth0_client_secret,
    auth0_domain,
    callback_path: '/auth/auth0/callback',
    authorize_options: ['login_hint']
  )
end