Add dotenv-mono binary

[IlyaSemenov]

Similar to what https://www.npmjs.com/package/dotenv-cli does, can we additionally export dotenv-mono as a executable script?

That would allow to replace the ugly NODE_OPTIONS='-r dotenv-mono/load' vite-node --script src/rake.ts with dotenv-mono -- vite-node --script src/rake.ts. That would even allow to use dotenv-mono to run non-node scripts.