Add option to rspec:install generator to configure for Selenium in Docker

[unikitty37]

Is your feature request related to a problem? Please describe.
When I run rails new and don't skip tests, system tests, or Docker, it creates a Docker container for Selenium and installs this in test/application_system_test_case.rb:

require "test_helper"

class ApplicationSystemTestCase < ActionDispatch::SystemTestCase
  if ENV["CAPYBARA_SERVER_PORT"]
    served_by host: "rails-app", port: ENV["CAPYBARA_SERVER_PORT"]

    driven_by :selenium, using: :headless_chrome, screen_size: [ 1400, 1400 ], options: {
      browser: :remote,
      url: "http://#{ENV["SELENIUM_HOST"]}:4444"
    }
  else
    driven_by :selenium, using: :headless_chrome, screen_size: [ 1400, 1400 ]
  end
end

rails g rspec:install doesn't do anything to set Selenium up, and getting system tests working is a nightmare as a result.

Describe the solution you'd like
It should be possible to pass the container name to the install generator, using syntax along the lines of rails g rspec:install --selenium-container=selenium and the generator should then provide a basic setup similar to the one rails new does for minitest.

Describe alternatives you've considered
Right now I'm considering just using Playwright for system tests, because I know I can get that working.

Additional context

[JonRowe]

👋 A PR would be accepted; I don't use Docker in my workflow and don't have the bandwidth to investigate this myself.