Improve generation of UUIDs

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Hey Andrew (thank you for Ahoy!), I was going through the code and noticed that it uses Math.random to generate the UUID, which is not recommended anymore even by the linked StackOverflow answer.

Here a quick update to use the crypto.randomUUID (if supported by the browser), otherwise falling back to the current recommended SO linked answer in the comment that now uses crypto.getRandomValues

On non-https pages the randomUUID won't be present, so it'll also fallback (getRandomValues works on http).