Rollup merge of #108349 - GuillaumeGomez:fix-duplicated-imports2, r=notriddle

rustdoc: Prevent duplicated imports

Fixes #108163.

Interestingly enough, the AST is providing us an import for each corresponding item, even though the `Res` links to multiple ones each time, which leaded to the same import being duplicated.

So in this PR, I decided to prevent the add of the import before the clean pass. However, I originally took a different path by instead filtering after cleaning the path. You can see it [here](https://github.com/rust-lang/rust/compare/master...GuillaumeGomez:rust:fix-duplicated-imports?expand=1). Only the second commit differs.

I think this approach is better though, but at least we can compare both if we want.

The first commit adds the check for duplicated items in the rustdoc-json output as asked in #108163.

cc `@aDotInTheVoid`
r? `@notriddle`

0 files changed, 0 insertions, 0 deletions