Rollup merge of #107555 - edward-shen:edward-shen/dup-trait-suggestion, r=compiler...

Rollup merge of #107555 - edward-shen:edward-shen/dup-trait-suggestion, r=compiler-errors

Modify existing bounds if they exist

Fixes #107335.

This implementation is kinda gross but I don't really see a better way to do it.

This primarily does two things: Modifies `suggest_constraining_type_param` to accept a new parameter that indicates a span to be replaced instead of added, if presented, and limit the additive suggestions to either suggest a new bound on an existing bound (see newly added unit test) or add the generics argument if a generics argument wasn't found.

The former change is required to retain the capability to add an entirely new bounds if it was entirely omitted.

r? ``@compiler-errors``