Allows passing size or custom alphabet via cli as args

[vitalybaev]

Closes #275

I've implemented minimal args parsing logic to fit our needs and be as little as possible

[ai]

We need to improve test coverage. You can check test coverage locally by running pnpm test.

[ai]

We also need to fix Node.js 12 support for binary (we can’t use ??)

[vitalybaev]

Done

I've faced error ERROR dual-publish error: Rename bin/utils.js to bin/utils/index.js, so I moved file according to this message.

Now it still works with Node 12 and test coverage is 100%

[ai]

bin/utils will create unnecessary files because of dual-publish. I cleaned up arguments parsing a little 27eaa90

And released in 3.2.