java-shell package should use proper crypto.randomBytes() polyfill

The JS BSON package wants a cryptographically secure randomness source. We use Math.random() here, but that’s not a proper long-term solution:

https://github.com/mongodb-js/mongosh/blob/9e5c1c2184554b6fe2eab8662669a52da219ab88/packages/java-shell/src/main/js/all.js#L1-L3