Add CLI Argument for Custom Indentation Length

[anders130]

First, I'd like to say: This formatter is amazing. The style guide it follows is excellent. However, there's one aspect I'd like to customize for my personal use: the indentation length.

I prefer using 4 spaces for indentation instead of the default 2 spaces. Unfortunately, I'm not proficient in Rust, so I'm not sure what changes are required to achieve this.

A nice solution would be to have a CLI argument (such as -i or --indent) that allows users to override the default indentation length.

[ZainKergaye]

I agree, is there an easy way to modify the indentation style? I want to use 4 spaces aswell.