Update jasmine rake task and gh action

We don't get a jasmine rake task so need
to create one in the Rakefile.

jasmine-browser-runner also expects chrome to be
installed so this adds an action to set it up. The
'setup-chrome' action defaults to using the latest
version so it doesn't need to be specified.

We use chrome and not chromedriver, to match the
expected use for jasmine-browser-runner:

https://github.com/jasmine/jasmine-browser-runner/blob/main/release_notes/2.3.0.md

Rakefile

@@ -4,7 +4,16 @@ require "jasmine"
 
 RSpec::Core::RakeTask.new(:spec)
 
-load "jasmine/tasks/jasmine.rake"
+namespace :jasmine do
+  desc "Test JavaScript with headless browser"
+  task :ci do
+    sh "npm test"
+  end
+  desc "Test JavaScript in browser"
+  task :server do
+    sh "npm run test-server"
+  end
+end
 
 desc "Lint Ruby and JavaScript"
 task :lint do