Group imports from the same crate

What it does

If two imports from the same crates are done using two different use keywords, clippy should suggest the user to group these using brackets.

Advantage

Make the code cleaner by being able to identify the dependencies from a given crate.

Drawbacks

Using different lines for different modules should be allowed; for instance:

use std::io::Write;
use std::time::Instant;

In this example, using two lines makes sense since io and time are two different modules.

Example

use std::io::Read;
use std::io::Write;

Could be written as:

use std::io::{Read, Write};

No implementation files or tests are named. Start by locating Clippy's existing import-related lint entry points and tests, then compare them with the separate-module example in this issue. Done means suggesting grouped braces for repeated imports from one crate while leaving imports from different modules separate.