As this is a lint about "style", and a purely cosmetical choice (using `<A: Trait>` over `impl Trait`), a lot of other files needed to be allowed this lint.
Those lints are trait_duplication_in_bounds and
type_repetition_in_bounds. I don't think those can be fixed on the
Clippy side alone, but need changes in the compiler. So let's move them
to nursery to get the sync through and then fix them on the rustc side.
Also adds a regression test that has to be fixed before they can be
moved back to pedantic.
