wip: example with rollup

[oliveriosousa]

This PR is a WIP example of bundling IPFS using RollupJS.

Since js-ipfs uses CommonJS and RollupJS is an ESModule bundler the setup requires some additional configuration.
To overcome this, it was imported the following necessary plugins:

• @rollup/plugin-commonjs: Plugin to convert CommonJS modules to ES6, so they can be included in a Rollup bundle
• @rollup/plugin-json: Plugin which Converts .json files to ES6 modules.
• @rollup/plugin-node-resolve: Plugin which locates modules using the Node resolution algorithm, for using third party modules in node_modules.
• snowpackjs/rollup-plugin-polyfill-node: A modern Node.js polyfill for your Rollup bundle.

See: rollup.config.js

But it is getting some errors when performing the bundle,

(!) Circular dependencies (!) Circular dependencies polyfill-node.global.js -> polyfill-node.global.js node_modules/ipfs-bitswap/src/types/message/index.js -> node_modules/ipfs-bitswap/src/types/message/entry.js -> node_modules/ipfs-bitswap/src/types/wantlist/index.js -> node_modules/ipfs-bitswap/src/types/message/index.js node_modules/ipfs-bitswap/src/types/message/index.js -> node_modules/ipfs-bitswap/src/types/message/entry.js -> node_modules/ipfs-bitswap/src/types/wantlist/index.js -> /Users/oliveriosousa/Projects/PL/js-ipfs-examples/examples/browser-rollup/node_modules/ipfs-bitswap/src/types/message/index.js?commonjs-proxy -> node_modules/ipfs-bitswap/src/types/message/index.js

Even with circular dependencies, rollup generates a js file but when used by the app it is possible to check some mistakes, such as:

const isElectron$1 = require('is-electron');

console in the browser:

index.js:289 Uncaught ReferenceError: require is not defined

Any suggestions?

TODO

• Fix bundle configuration
• Add tests
• Improve example
• Improve readme

cc @hugomrdias

[achingbrain]

Since js-ipfs uses CommonJS

js-ipfs is all ESM now, so you may be able to simplify this a bit. Most deps are still CJS though.