Add browser testing

[sfroment]

Browser testing

The idea is to have a test with a headless browser with one of the examples to be sure before merging that nothing broke.

How to do

• Probably use some e2e framework, (cypress, playright, puppeteer ...)
• Run at least 2 instance of the browser
• Check the bootstrap peers are appearing
• Check that the 2 browser can connect to the same CRO and see each other
• Check that they can receive the update from the other instance (like if we use the grid make sure we receive the movement, or if chat that we receive the message...)

[sfroment]

fixed by: #343