Group imports by their visibilities

[kafji]

Hi. This is a patch for feature request #5696 and #4070.

This patch adds another variant, Visiblity to group_imports that turn

Unordered:

pub(super) use chrono::Utc;
pub use super::update::convert_publish_payload;

pub(crate) use juniper::{FieldError, FieldResult};
pub(in crate::models) use uuid::Uuid;
use alloc::alloc::Layout;

use std::sync::Arc;

pub(self) use broker::database::PooledConnection;

use super::schema::{Context, Payload};
use core::f32;
pub use crate::models::Event;

into

Ordered:

use super::schema::{Context, Payload};
use alloc::alloc::Layout;
use core::f32;
use std::sync::Arc;

pub(self) use broker::database::PooledConnection;

pub(super) use chrono::Utc;

pub(crate) use juniper::{FieldError, FieldResult};

pub(in crate::models) use uuid::Uuid;

pub use super::update::convert_publish_payload;
pub use crate::models::Event;

I opt to order the imports from the least visible to the most to make exporting imported declaration look more natural, for example:

use proto::*;

pub use proto::Response;

pub fn send_request() -> Response { ... }

[kafji]

crate export for reorder module

[ytmimi]

Just taking a quick glance at the tests, and was wondering why an existing test changed?