Add Browser ES module build

[Kolezhniuk]

Add Browser ES module build

Why?

• Out team is using snarkjs package in our project https://github.com/0xPolygonID/js-sdk and faced with issue that ES build for browser is not working. It works fine with snarkjs bundle for browser, but there are some disadvantages:
  1. it's need to include this bundle in scripts in your html file and load whole snark js bundle even (if you using certain functions)
  2. Developer experience wish to be better because this approach requires to operate with snarkjs lib as property of window object

Advantages of using ES module build:

1. No additional manipulations with NodeJS dependenices from bundler perspective (Webpack, Esbuild, Vite etc) in case you want to use this package in the browser. Simple install npm i ffjavascript and you can easily use it for example in Angular or React
2. Support of Tree shaking

What is changed?

• Updated Rollup
• Create Rollup config to assemble ES module for browser
• Update package.json to use browser.esm.js in case of browser usage

What is next

• update snarkjs package in similar way Add Browser ES module build #127

UDP: in theory issue #29 should be fixed by this PR

[phated]

A browser bundle is unnecessary here. Perhaps you want to remove process.browser checks so the modules work directly in bundlers. Alternatively, we can use the exports section to switch specific files between a nodejs implementation and a non-node version.

[Kolezhniuk]

@phated

A browser bundle is unnecessary here. Perhaps you want to remove process.browser checks so the modules work directly in bundlers. Alternatively, we can use the exports section to switch specific files between a nodejs implementation and a non-node version.

Hello!
Let me explain more clearly what also has been fixed in this PR:

1. Support clear ES module build directly for browser (without node os crypto dependencies)
2. Added check https://github.com/iden3/ffjavascript/pull/127/files#diff-0462ab1425fcb10bd181dc4f7513067635628058d4c1d851666e2b10a64ec2f4R98
3. Added ability to run multi theading mode for some frontend frameworks (Angular, AngularJS, Ember.js, JQuery...)
   which is currently failing

Could you please explain in more detail why you have concerns about not having a browser bundle?

[phated]

A browser bundle is not required. Node 20+ has the global Crypto API, so we should remove the process.browser usage and remove any node-specific imports.

[OBrezhniev]

Browser bundle is built anyway in SnarkJS, this PR simplifies life for people using ffjavascript directly in the browser, and unblocks creation of SnarkJS build that works fine with Angular and other frontend frameworks.

Nodejs compatibility with the browser crypto api is nice, but wasn't in the scope of this PR. And process.browser workaround is still needed for switching between os.cpus().length and navigator.hardwareConcurrency.