Rollup merge of #95260 - compiler-errors:fn, r=davidtwco

Rollup merge of #95260 - compiler-errors:fn, r=davidtwco

Better suggestions for `Fn`-family trait selection errors

1. Suppress suggestions to add `std::ops::Fn{,Mut,Once}` bounds when a type already implements `Fn{,Mut,Once}`
2. Add a note that points out that a type does in fact implement `Fn{,Mut,Once}`, but the arguments vary (either by number or by actual arguments)
3. Add a note that points out that a type does in fact implement `Fn{,Mut,Once}`, but not the right one (e.g. implements `FnMut`, but `Fn` is required).

Fixes #95147