SIMID-308: Update sample to use web.crypto for generating session IDs.

[nchavez324]

This still generates a v4 UUID, as before. I chose crypto.getRandomValues over crypto.randomUUID since it supports much older browsers including IE, and doesn't require a secure context (HTTPS or localhost).

308

I'll update the spec to include notes about using a cryptographically secure method in a separate PR.