Create an example of using FrontendServer and context.ExecuteJavascriptTestAsync() (OSOE-904)

[sarahelsaig]

This is a followup of #407. As mentioned in #407 (comment) there should be a sample test with demonstration to make these features accessible.

• Create a setup method demonstrating FrontendServer using a simple-to-setup standalone web server. Ideally something we can initiate directly from CLI without any setup code. http-server from NPM may be a good candidate.
• Add test interacting with this frontend with the usual comment documentations.
• The same, selenium node.js. (may need some code generalized and migrated from OFFI)
• Add mention and links to Readme.md.

Jira issue