Suggest renaming import if names clash

[Cldfire]

Closes #32354.

The output for the example in the issue looks like this:

~/p/local-rust-dev-testing ❯❯❯ cargo +local-s1 build
   Compiling local-rust-dev-testing v0.1.0 (file:///home/cldfire/programming_projects/local-rust-dev-testing)
error[E0252]: the name `ConstructorExtension` is defined multiple times
  --> src/main.rs:49:5
   |
48 | use extension1::ConstructorExtension;
   |     -------------------------------- previous import of the trait `ConstructorExtension` here
49 | use extension2::ConstructorExtension;
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `ConstructorExtension` reimported here
   |
   = note: `ConstructorExtension` must be defined only once in the type namespace of this module
help: You can use `as` to change the binding name of the import
   |
49 | use extension2::ConstructorExtension as OtherConstructorExtension;
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

...

This is my first PR that touches the compiler in any way, so if there's something else I need to do here (e.g. add a test), please let me know :).

[rust-highfive]

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @pnkfelix (or someone else) soon.

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[estebank]

Looks great! Could you add a test for it? Just create an .rs file in src/test/ui/suggestions with a descriptive name, run the tests (./x.py test src/test/ui --stage 1) which will fail due to the new test file, and run src/test/ui/update-all-references.sh ../../../build/<YOUR_ENV>/test/ui. Doing so will create a new .stderr file with the compiler output to test against. If you test again they should pass now.

Otherwise, r=me.

[Cldfire]

Added a stripped-down version of the example from the issue as the test.

[estebank]

@bors r+ rollup

[bors]

📌 Commit 61396a8 has been approved by estebank