fix: polyfill buffer, shim randombytes

[phanshiyu]

What

1. remove direct use of crypto and instead use https://www.npmjs.com/package/randombytes, which uses native crypto methods based on environment
2. use https://www.npmjs.com/package/buffer instead of relying on buffer from node env

Tested

1. CRA - works out of the box
2. React vite needs

   // vite.config.ts
   export default defineConfig({
   plugins: [react()],
   define: {
   // By default, Vite doesn't include shims for NodeJS/
   // necessary for segment analytics lib to work
   global: 'globalThis'
   },  
   })

3. next server side - out of the box
4. next client side - have to install undici

[github-actions[bot]]

:tada: This PR is included in version 6.10.0-alpha.5 :tada:

The release is available on:

• npm package (@alpha dist-tag)
• GitHub release

Your semantic-release bot :package::rocket: