Support for .env files

[jonit-dev]

Current Behavior

It seems that tsdx doesn't have support for loading .env files.
Even when adding a custom tsdx.config.js with this plugin, it loads variables as undefined.

Desired Behavior

Load .env files properly.

[eliezer-souza]

@jonit-dev It worked for me that way

const dotenv = require('rollup-plugin-dotenv');

module.exports = {
  rollup(config, options) {
    config.plugins.unshift(dotenv.default());

    return config;
  },
};