Introduce a few system tests

Primarily I'm trying to exercise active storage and action cable /
turbo streams, both of which have been brittle when making changes to
tenanting.

test/application_system_test_case.rb

@@ -1,5 +1,31 @@
 require "test_helper"
 
 class ApplicationSystemTestCase < ActionDispatch::SystemTestCase
-  driven_by :selenium, using: :chrome, screen_size: [ 1400, 1400 ]
+  browser_options = Selenium::WebDriver::Chrome::Options.new.tap do |opts|
+    opts.add_argument("--window-size=1200,800")
+    opts.add_argument("--disable-extensions")
+    # Disable non-foreground tabs from getting a lower process priority
+    opts.add_argument("--disable-renderer-backgrounding")
+    # Normally, Chrome will treat a 'foreground' tab instead as backgrounded if the surrounding
+    # window is occluded (aka visually covered) by another window. This flag disables that.
+    opts.add_argument("--disable-backgrounding-occluded-windows")
+    # Suppress all permission prompts by automatically denying them.
+    opts.add_argument("--deny-permission-prompts")
+    opts.add_argument("--enable-automation")
+  end
+
+  Capybara.register_driver :chrome_headless do |app|
+    browser_options.add_argument("--headless")
+    Capybara::Selenium::Driver.new(app, browser: :chrome, options: browser_options)
+  end
+
+  Capybara.register_driver :chrome do |app|
+    Capybara::Selenium::Driver.new(app, browser: :chrome, options: browser_options)
+  end
+
+  if ENV["SYSTEM_TESTS_BROWSER"]
+    driven_by :chrome, screen_size: [ 1200, 1000 ]
+  else
+    driven_by :chrome_headless, screen_size: [ 1200, 1000 ]
+  end
 end