Bundle icon files

[epessina]

The icon files shipped with the package following #477 have the same structure as the react-icons ones, meaning that each icon is represented through a js file that internally imports (or requires) the function GenIcon exposed by a lib directory (which is also shipped with the icons).

For example:

var GenIcon = require('../lib').GenIcon
module.exports.AiFillAccountBook = function AiFillAccountBook (props) {
  return GenIcon({ /* icons svg tree */ })(props);
};

We should consider making icon files auto-conclusive bundling the GenIcon function or directly shipping the result of GenIcon parametrized with the props. This would help with dynamic import since the fetched js code should not need to perform import when executed.