[Feature] Add group_imports rule to .rustfmt.toml

[damirka]

🚀 Feature

Given number of comments related to imports section which @howardwu left in my CLI PR (#632) I suggest adding new rule for grouping imports in .rustfmt.toml file - group_imports.

See param description here (link).
Example output:

use std::path::PathBuf;

use pest_ast::FromPest;
use serde::Serialize;

use crate::ast::Rule;

Motivation

We already have similar code style internally and instead of fixing it manually we can apply new rule to formatter.

Implementation

# .rustfmt.toml
group_imports = "StdExternalCrate"

[damirka]

Closing as have not received enough interest rn.