Recover from missing `crate` or other scope resolution in `use` where appropriate

[Rageking8]

Given the following code: link

trait Trait {}

mod a {
    use Trait;
}

fn main() {}

The current output is:

Compiling playground v0.0.1 (/playground)
error[[E0432]](https://doc.rust-lang.org/nightly/error-index.html#E0432): unresolved import `Trait`
 --> src/main.rs:4:9
  |
4 |     use Trait;
  |         ^^^^^ no external crate `Trait`

For more information about this error, try `rustc --explain E0432`.
error: could not compile `playground` due to previous error

Ideally the output can look something like this:

Compiling playground v0.0.1 (/playground)
error[[E0432]](https://doc.rust-lang.org/nightly/error-index.html#E0432): unresolved import `Trait`
 --> src/main.rs:4:9
  |
4 |     use Trait;
  |         ^^^^^ no external crate `Trait`
  |
help: add `crate::` to import trait `Trait`
  |
4 |     use crate::Trait;
  |         +++++++

For more information about this error, try `rustc --explain E0432`.
error: could not compile `playground` due to previous error

This can also be extended to other items such as functions and variables. The help should only be emitted if an exact match exist in the parent scope and the scope resolution used is incorrect. Thanks.

[Noratrieb]

We already have similar logic for normal uses of items

trait Trait {}

mod a {
    impl Trait for () {}
}

fn main() {}

error[E0405]): cannot find trait `Trait` in this scope
 --> src/main.rs:4:10
  |
4 |     impl Trait for () {}
  |          ^^^^^ not found in this scope
  |
help: consider importing one of these items
  |
4 |     use crate::Trait;
  |
4 |     use traitobject::Trait;
  |